CINXE.COM

<!DOCTYPE html> <html class="client-nojs vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-sticky-header-enabled vector-toc-available" lang="en" dir="ltr"> <head> <meta charset="UTF-8"> <title>Specification pattern - Wikipedia</title> <script>(function(){var className="client-js vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-sticky-header-enabled vector-toc-available";var cookie=document.cookie.match(/(?:^|; )enwikimwclientpreferences=([^;]+)/);if(cookie){cookie[1].split('%2C').forEach(function(pref){className=className.replace(new RegExp('(^| )'+pref.replace(/-clientpref-\w+$|[^\w-]+/g,'')+'-clientpref-\\w+( |$)'),'$1'+pref+'$2');});}document.documentElement.className=className;}());RLCONF={"wgBreakFrames":false,"wgSeparatorTransformTable":["",""],"wgDigitTransformTable":["",""],"wgDefaultDateFormat":"dmy","wgMonthNames":["","January","February","March","April","May","June","July","August","September","October","November","December"],"wgRequestId":"3d2aa979-d7de-4da1-a46c-d6eaab994618","wgCanonicalNamespace":"","wgCanonicalSpecialPageName":false,"wgNamespaceNumber":0,"wgPageName":"Specification_pattern","wgTitle":"Specification pattern","wgCurRevisionId":1238065670,"wgRevisionId":1238065670,"wgArticleId":12088522,"wgIsArticle":true,"wgIsRedirect":false,"wgAction":"view","wgUserName":null,"wgUserGroups":["*"],"wgCategories":["Articles with short description","Short description is different from Wikidata","Articles with example C Sharp code","Articles with example C++ code","Articles with example JavaScript code","Articles with example Python (programming language) code","Architectural pattern (computer science)","Software design patterns","Programming language comparisons"],"wgPageViewLanguage":"en","wgPageContentLanguage":"en","wgPageContentModel":"wikitext","wgRelevantPageName":"Specification_pattern","wgRelevantArticleId":12088522,"wgIsProbablyEditable":true,"wgRelevantPageIsProbablyEditable":true,"wgRestrictionEdit":[],"wgRestrictionMove":[],"wgNoticeProject":"wikipedia","wgCiteReferencePreviewsActive":false,"wgFlaggedRevsParams":{"tags":{"status":{"levels":1}}},"wgMediaViewerOnClick":true,"wgMediaViewerEnabledByDefault":true,"wgPopupsFlags":0,"wgVisualEditor":{"pageLanguageCode":"en","pageLanguageDir":"ltr","pageVariantFallbacks":"en"},"wgMFDisplayWikibaseDescriptions":{"search":true,"watchlist":true,"tagline":false,"nearby":true},"wgWMESchemaEditAttemptStepOversample":false,"wgWMEPageLength":20000,"wgEditSubmitButtonLabelPublish":true,"wgULSPosition":"interlanguage","wgULSisCompactLinksEnabled":false,"wgVector2022LanguageInHeader":true,"wgULSisLanguageSelectorEmpty":false,"wgWikibaseItemId":"Q7575013","wgCheckUserClientHintsHeadersJsApi":["brands","architecture","bitness","fullVersionList","mobile","model","platform","platformVersion"],"GEHomepageSuggestedEditsEnableTopics":true,"wgGETopicsMatchModeEnabled":false,"wgGEStructuredTaskRejectionReasonTextInputEnabled":false,"wgGELevelingUpEnabledForUser":false}; RLSTATE={"ext.globalCssJs.user.styles":"ready","site.styles":"ready","user.styles":"ready","ext.globalCssJs.user":"ready","user":"ready","user.options":"loading","ext.pygments":"ready","skins.vector.search.codex.styles":"ready","skins.vector.styles":"ready","skins.vector.icons":"ready","jquery.makeCollapsible.styles":"ready","ext.wikimediamessages.styles":"ready","ext.visualEditor.desktopArticleTarget.noscript":"ready","ext.uls.interlanguage":"ready","wikibase.client.init":"ready"};RLPAGEMODULES=["ext.pygments.view","mediawiki.page.media","site","mediawiki.page.ready","jquery.makeCollapsible","mediawiki.toc","skins.vector.js","ext.centralNotice.geoIP","ext.centralNotice.startUp","ext.gadget.ReferenceTooltips","ext.gadget.switcher","ext.urlShortener.toolbar","ext.centralauth.centralautologin","mmv.bootstrap","ext.popups","ext.visualEditor.desktopArticleTarget.init","ext.visualEditor.targetLoader","ext.echo.centralauth","ext.eventLogging","ext.wikimediaEvents","ext.navigationTiming","ext.uls.interface","ext.cx.eventlogging.campaigns","ext.cx.uls.quick.actions","wikibase.client.vector-2022","ext.checkUser.clientHints","ext.growthExperiments.SuggestedEditSession"];</script> <script>(RLQ=window.RLQ||[]).push(function(){mw.loader.impl(function(){return["user.options@12s5i",function($,jQuery,require,module){mw.user.tokens.set({"patrolToken":"+\\","watchToken":"+\\","csrfToken":"+\\"}); }];});});</script> <link rel="stylesheet" href="/w/load.php?lang=en&modules=ext.pygments%7Cext.uls.interlanguage%7Cext.visualEditor.desktopArticleTarget.noscript%7Cext.wikimediamessages.styles%7Cjquery.makeCollapsible.styles%7Cskins.vector.icons%2Cstyles%7Cskins.vector.search.codex.styles%7Cwikibase.client.init&only=styles&skin=vector-2022"> <script async="" src="/w/load.php?lang=en&modules=startup&only=scripts&raw=1&skin=vector-2022"></script> <meta name="ResourceLoaderDynamicStyles" content=""> <link rel="stylesheet" href="/w/load.php?lang=en&modules=site.styles&only=styles&skin=vector-2022"> <meta name="generator" content="MediaWiki 1.44.0-wmf.20"> <meta name="referrer" content="origin"> <meta name="referrer" content="origin-when-cross-origin"> <meta name="robots" content="max-image-preview:standard"> <meta name="format-detection" content="telephone=no"> <meta property="og:image" content="https://upload.wikimedia.org/wikipedia/commons/4/46/Specification_UML.png"> <meta property="og:image:width" content="1200"> <meta property="og:image:height" content="716"> <meta property="og:image" content="https://upload.wikimedia.org/wikipedia/commons/4/46/Specification_UML.png"> <meta property="og:image:width" content="800"> <meta property="og:image:height" content="478"> <meta property="og:image:width" content="640"> <meta property="og:image:height" content="382"> <meta name="viewport" content="width=1120"> <meta property="og:title" content="Specification pattern - Wikipedia"> <meta property="og:type" content="website"> <link rel="preconnect" href="//upload.wikimedia.org"> <link rel="alternate" media="only screen and (max-width: 640px)" href="//en.m.wikipedia.org/wiki/Specification_pattern"> <link rel="alternate" type="application/x-wiki" title="Edit this page" href="/w/index.php?title=Specification_pattern&action=edit"> <link rel="apple-touch-icon" href="/static/apple-touch/wikipedia.png"> <link rel="icon" href="/static/favicon/wikipedia.ico"> <link rel="search" type="application/opensearchdescription+xml" href="/w/rest.php/v1/search" title="Wikipedia (en)"> <link rel="EditURI" type="application/rsd+xml" href="//en.wikipedia.org/w/api.php?action=rsd"> <link rel="canonical" href="https://en.wikipedia.org/wiki/Specification_pattern"> <link rel="license" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en"> <link rel="alternate" type="application/atom+xml" title="Wikipedia Atom feed" href="/w/index.php?title=Special:RecentChanges&feed=atom"> <link rel="dns-prefetch" href="//meta.wikimedia.org" /> <link rel="dns-prefetch" href="login.wikimedia.org"> </head> <body class="skin--responsive skin-vector skin-vector-search-vue mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject mw-editable page-Specification_pattern rootpage-Specification_pattern skin-vector-2022 action-view"><a class="mw-jump-link" href="#bodyContent">Jump to content</a> <div class="vector-header-container"> <header class="vector-header mw-header"> <div class="vector-header-start"> <nav class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-dropdown" class="vector-dropdown vector-main-menu-dropdown vector-button-flush-left vector-button-flush-right" title="Main menu" > <input type="checkbox" id="vector-main-menu-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-main-menu-dropdown" class="vector-dropdown-checkbox " aria-label="Main menu" > <label id="vector-main-menu-dropdown-label" for="vector-main-menu-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" > Main menu </label> <div class="vector-dropdown-content"> <div id="vector-main-menu-unpinned-container" class="vector-unpinned-container"> <div id="vector-main-menu" class="vector-main-menu vector-pinnable-element"> <div class="vector-pinnable-header vector-main-menu-pinnable-header vector-pinnable-header-unpinned" data-feature-name="main-menu-pinned" data-pinnable-element-id="vector-main-menu" data-pinned-container-id="vector-main-menu-pinned-container" data-unpinned-container-id="vector-main-menu-unpinned-container" > <div class="vector-pinnable-header-label">Main menu</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-main-menu.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-main-menu.unpin">hide</button> </div> <div id="p-navigation" class="vector-menu mw-portlet mw-portlet-navigation" > <div class="vector-menu-heading"> Navigation </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-mainpage-description" class="mw-list-item"><a href="/wiki/Main_Page" title="Visit the main page [z]" accesskey="z">Main page</a></li><li id="n-contents" class="mw-list-item"><a href="/wiki/Wikipedia:Contents" title="Guides to browsing Wikipedia">Contents</a></li><li id="n-currentevents" class="mw-list-item"><a href="/wiki/Portal:Current_events" title="Articles related to current events">Current events</a></li><li id="n-randompage" class="mw-list-item"><a href="/wiki/Special:Random" title="Visit a randomly selected article [x]" accesskey="x">Random article</a></li><li id="n-aboutsite" class="mw-list-item"><a href="/wiki/Wikipedia:About" title="Learn about Wikipedia and how it works">About Wikipedia</a></li><li id="n-contactpage" class="mw-list-item"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us" title="How to contact Wikipedia">Contact us</a></li> </ul> </div> </div> <div id="p-interaction" class="vector-menu mw-portlet mw-portlet-interaction" > <div class="vector-menu-heading"> Contribute </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-help" class="mw-list-item"><a href="/wiki/Help:Contents" title="Guidance on how to use and edit Wikipedia">Help</a></li><li id="n-introduction" class="mw-list-item"><a href="/wiki/Help:Introduction" title="Learn how to edit Wikipedia">Learn to edit</a></li><li id="n-portal" class="mw-list-item"><a href="/wiki/Wikipedia:Community_portal" title="The hub for editors">Community portal</a></li><li id="n-recentchanges" class="mw-list-item"><a href="/wiki/Special:RecentChanges" title="A list of recent changes to Wikipedia [r]" accesskey="r">Recent changes</a></li><li id="n-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_upload_wizard" title="Add images or other media for use on Wikipedia">Upload file</a></li><li id="n-specialpages" class="mw-list-item"><a href="/wiki/Special:SpecialPages">Special pages</a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> <a href="/wiki/Main_Page" class="mw-logo"> <img class="mw-logo-icon" src="/static/images/icons/wikipedia.png" alt="" aria-hidden="true" height="50" width="50"> <img class="mw-logo-wordmark" alt="Wikipedia" src="/static/images/mobile/copyright/wikipedia-wordmark-en.svg" style="width: 7.5em; height: 1.125em;"> <img class="mw-logo-tagline" alt="The Free Encyclopedia" src="/static/images/mobile/copyright/wikipedia-tagline-en.svg" width="117" height="13" style="width: 7.3125em; height: 0.8125em;"> </a> </div> <div class="vector-header-end"> <div id="p-search" role="search" class="vector-search-box-vue vector-search-box-collapses vector-search-box-show-thumbnail vector-search-box-auto-expand-width vector-search-box"> <a href="/wiki/Special:Search" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only search-toggle" title="Search Wikipedia [f]" accesskey="f"> Search </a> <div class="vector-typeahead-search-container"> <div class="cdx-typeahead-search cdx-typeahead-search--show-thumbnail cdx-typeahead-search--auto-expand-width"> <form action="/w/index.php" id="searchform" class="cdx-search-input cdx-search-input--has-end-button"> <div id="simpleSearch" class="cdx-search-input__input-wrapper" data-search-loc="header-moved"> <div class="cdx-text-input cdx-text-input--has-start-icon"> <input class="cdx-text-input__input" type="search" name="search" placeholder="Search Wikipedia" aria-label="Search Wikipedia" autocapitalize="sentences" title="Search Wikipedia [f]" accesskey="f" id="searchInput" > </div> <input type="hidden" name="title" value="Special:Search"> </div> <button class="cdx-button cdx-search-input__end-button">Search</button> </form> </div> </div> </div> <nav class="vector-user-links vector-user-links-wide" aria-label="Personal tools"> <div class="vector-user-links-main"> <div id="p-vector-user-menu-preferences" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-userpage" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-dropdown" class="vector-dropdown " title="Change the appearance of the page's font size, width, and color" > <input type="checkbox" id="vector-appearance-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-appearance-dropdown" class="vector-dropdown-checkbox " aria-label="Appearance" > <label id="vector-appearance-dropdown-label" for="vector-appearance-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" > Appearance </label> <div class="vector-dropdown-content"> <div id="vector-appearance-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <div id="p-vector-user-menu-notifications" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-overflow" class="vector-menu mw-portlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="https://donate.wikimedia.org/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en" class="">Donate</a> </li> <li id="pt-createaccount-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:CreateAccount&returnto=Specification+pattern" title="You are encouraged to create an account and log in; however, it is not mandatory" class="">Create account</a> </li> <li id="pt-login-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:UserLogin&returnto=Specification+pattern" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o" class="">Log in</a> </li> </ul> </div> </div> </div> <div id="vector-user-links-dropdown" class="vector-dropdown vector-user-menu vector-button-flush-right vector-user-menu-logged-out" title="Log in and more options" > <input type="checkbox" id="vector-user-links-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-user-links-dropdown" class="vector-dropdown-checkbox " aria-label="Personal tools" > <label id="vector-user-links-dropdown-label" for="vector-user-links-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" > Personal tools </label> <div class="vector-dropdown-content"> <div id="p-personal" class="vector-menu mw-portlet mw-portlet-personal user-links-collapsible-item" title="User menu" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport" class="user-links-collapsible-item mw-list-item"><a href="https://donate.wikimedia.org/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en">Donate</a></li><li id="pt-createaccount" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:CreateAccount&returnto=Specification+pattern" title="You are encouraged to create an account and log in; however, it is not mandatory"> Create account</a></li><li id="pt-login" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:UserLogin&returnto=Specification+pattern" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o"> Log in</a></li> </ul> </div> </div> <div id="p-user-menu-anon-editor" class="vector-menu mw-portlet mw-portlet-user-menu-anon-editor" > <div class="vector-menu-heading"> Pages for logged out editors <a href="/wiki/Help:Introduction" aria-label="Learn more about editing">learn more</a> </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-anoncontribs" class="mw-list-item"><a href="/wiki/Special:MyContributions" title="A list of edits made from this IP address [y]" accesskey="y">Contributions</a></li><li id="pt-anontalk" class="mw-list-item"><a href="/wiki/Special:MyTalk" title="Discussion about edits from this IP address [n]" accesskey="n">Talk</a></li> </ul> </div> </div> </div> </div> </nav> </div> </header> </div> <div class="mw-page-container"> <div class="mw-page-container-inner"> <div class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Contents" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Contents</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-Code_examples" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Code_examples"> <div class="vector-toc-text"> 1 Code examples </div> </a> <button aria-controls="toc-Code_examples-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Code examples subsection </button> <ul id="toc-Code_examples-sublist" class="vector-toc-list"> <li id="toc-C#" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#C#"> <div class="vector-toc-text"> 1.1 C# </div> </a> <ul id="toc-C#-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-C#_6.0_with_generics" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#C#_6.0_with_generics"> <div class="vector-toc-text"> 1.2 C# 6.0 with generics </div> </a> <ul id="toc-C#_6.0_with_generics-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Python" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Python"> <div class="vector-toc-text"> 1.3 Python </div> </a> <ul id="toc-Python-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-C++" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#C++"> <div class="vector-toc-text"> 1.4 C++ </div> </a> <ul id="toc-C++-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-TypeScript" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#TypeScript"> <div class="vector-toc-text"> 1.5 TypeScript </div> </a> <ul id="toc-TypeScript-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Example_of_use" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Example_of_use"> <div class="vector-toc-text"> 2 Example of use </div> </a> <ul id="toc-Example_of_use-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> 3 References </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> 4 External links </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" title="Table of Contents" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" > Toggle the table of contents </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading">Specification pattern</h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 4 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-4" aria-hidden="true" > 4 languages </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%A1%D0%BF%D0%B5%D1%86%D0%B8%D1%84%D0%B8%D0%BA%D0%B0%D1%86%D0%B8%D1%8F_(%D1%88%D0%B0%D0%B1%D0%BB%D0%BE%D0%BD)" title="Спецификация (шаблон) – Bulgarian" lang="bg" hreflang="bg" data-title="Спецификация (шаблон)" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target">Български</a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Specifik%C3%A1ci%C3%B3_programtervez%C3%A9si_minta" title="Specifikáció programtervezési minta – Hungarian" lang="hu" hreflang="hu" data-title="Specifikáció programtervezési minta" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target">Magyar</a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A1%D0%BF%D0%B5%D1%86%D0%B8%D1%84%D0%B8%D0%BA%D0%B0%D1%86%D0%B8%D1%8F_(%D1%88%D0%B0%D0%B1%D0%BB%D0%BE%D0%BD_%D0%BF%D1%80%D0%BE%D0%B5%D0%BA%D1%82%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%B8%D1%8F)" title="Спецификация (шаблон проектирования) – Russian" lang="ru" hreflang="ru" data-title="Спецификация (шаблон проектирования)" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target">Русский</a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%A1%D0%BF%D0%B5%D1%86%D0%B8%D1%84%D1%96%D0%BA%D0%B0%D1%86%D1%96%D1%8F_(%D1%88%D0%B0%D0%B1%D0%BB%D0%BE%D0%BD_%D0%BF%D1%80%D0%BE%D1%94%D0%BA%D1%82%D1%83%D0%B2%D0%B0%D0%BD%D0%BD%D1%8F)" title="Специфікація (шаблон проєктування) – Ukrainian" lang="uk" hreflang="uk" data-title="Специфікація (шаблон проєктування)" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target">Українська</a></li> </ul> <div class="after-portlet after-portlet-lang"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q7575013#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Specification_pattern" title="View the content page [c]" accesskey="c">Article</a></li><li id="ca-talk" class="vector-tab-noicon mw-list-item"><a href="/wiki/Talk:Specification_pattern" rel="discussion" title="Discuss improvements to the content page [t]" accesskey="t">Talk</a></li> </ul> </div> </div> <div id="vector-variants-dropdown" class="vector-dropdown emptyPortlet" > <input type="checkbox" id="vector-variants-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-variants-dropdown" class="vector-dropdown-checkbox " aria-label="Change language variant" > <label id="vector-variants-dropdown-label" for="vector-variants-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" >English </label> <div class="vector-dropdown-content"> <div id="p-variants" class="vector-menu mw-portlet mw-portlet-variants emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> </div> </div> </nav> </div> <div id="right-navigation" class="vector-collapsible"> <nav aria-label="Views"> <div id="p-views" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-views" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-view" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Specification_pattern">Read</a></li><li id="ca-edit" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Specification_pattern&action=edit" title="Edit this page [e]" accesskey="e">Edit</a></li><li id="ca-history" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Specification_pattern&action=history" title="Past revisions of this page [h]" accesskey="h">View history</a></li> </ul> </div> </div> </nav> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-dropdown" class="vector-dropdown vector-page-tools-dropdown" > <input type="checkbox" id="vector-page-tools-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-tools-dropdown" class="vector-dropdown-checkbox " aria-label="Tools" > <label id="vector-page-tools-dropdown-label" for="vector-page-tools-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" >Tools </label> <div class="vector-dropdown-content"> <div id="vector-page-tools-unpinned-container" class="vector-unpinned-container"> <div id="vector-page-tools" class="vector-page-tools vector-pinnable-element"> <div class="vector-pinnable-header vector-page-tools-pinnable-header vector-pinnable-header-unpinned" data-feature-name="page-tools-pinned" data-pinnable-element-id="vector-page-tools" data-pinned-container-id="vector-page-tools-pinned-container" data-unpinned-container-id="vector-page-tools-unpinned-container" > <div class="vector-pinnable-header-label">Tools</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-page-tools.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-page-tools.unpin">hide</button> </div> <div id="p-cactions" class="vector-menu mw-portlet mw-portlet-cactions emptyPortlet vector-has-collapsible-items" title="More options" > <div class="vector-menu-heading"> Actions </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-more-view" class="selected vector-more-collapsible-item mw-list-item"><a href="/wiki/Specification_pattern">Read</a></li><li id="ca-more-edit" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Specification_pattern&action=edit" title="Edit this page [e]" accesskey="e">Edit</a></li><li id="ca-more-history" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Specification_pattern&action=history">View history</a></li> </ul> </div> </div> <div id="p-tb" class="vector-menu mw-portlet mw-portlet-tb" > <div class="vector-menu-heading"> General </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-whatlinkshere" class="mw-list-item"><a href="/wiki/Special:WhatLinksHere/Specification_pattern" title="List of all English Wikipedia pages containing links to this page [j]" accesskey="j">What links here</a></li><li id="t-recentchangeslinked" class="mw-list-item"><a href="/wiki/Special:RecentChangesLinked/Specification_pattern" rel="nofollow" title="Recent changes in pages linked from this page [k]" accesskey="k">Related changes</a></li><li id="t-upload" class="mw-list-item"><a href="//en.wikipedia.org/wiki/Wikipedia:File_Upload_Wizard" title="Upload files [u]" accesskey="u">Upload file</a></li><li id="t-permalink" class="mw-list-item"><a href="/w/index.php?title=Specification_pattern&oldid=1238065670" title="Permanent link to this revision of this page">Permanent link</a></li><li id="t-info" class="mw-list-item"><a href="/w/index.php?title=Specification_pattern&action=info" title="More information about this page">Page information</a></li><li id="t-cite" class="mw-list-item"><a href="/w/index.php?title=Special:CiteThisPage&page=Specification_pattern&id=1238065670&wpFormIdentifier=titleform" title="Information on how to cite this page">Cite this page</a></li><li id="t-urlshortener" class="mw-list-item"><a href="/w/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FSpecification_pattern">Get shortened URL</a></li><li id="t-urlshortener-qrcode" class="mw-list-item"><a href="/w/index.php?title=Special:QrCode&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FSpecification_pattern">Download QR code</a></li> </ul> </div> </div> <div id="p-coll-print_export" class="vector-menu mw-portlet mw-portlet-coll-print_export" > <div class="vector-menu-heading"> Print/export </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="coll-download-as-rl" class="mw-list-item"><a href="/w/index.php?title=Special:DownloadAsPdf&page=Specification_pattern&action=show-download-screen" title="Download this page as a PDF file">Download as PDF</a></li><li id="t-print" class="mw-list-item"><a href="/w/index.php?title=Specification_pattern&printable=yes" title="Printable version of this page [p]" accesskey="p">Printable version</a></li> </ul> </div> </div> <div id="p-wikibase-otherprojects" class="vector-menu mw-portlet mw-portlet-wikibase-otherprojects" > <div class="vector-menu-heading"> In other projects </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-wikibase" class="wb-otherproject-link wb-otherproject-wikibase-dataitem mw-list-item"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q7575013" title="Structured data on this page hosted by Wikidata [g]" accesskey="g">Wikidata item</a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> </div> </div> </div> <div class="vector-column-end"> <div class="vector-sticky-pinned-container"> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-pinned-container" class="vector-pinned-container"> </div> </nav> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Appearance</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Software design pattern</div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Specification_UML.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/46/Specification_UML.png/300px-Specification_UML.png" decoding="async" width="300" height="179" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/46/Specification_UML.png/450px-Specification_UML.png 1.5x, //upload.wikimedia.org/wikipedia/commons/4/46/Specification_UML.png 2x" data-file-width="541" data-file-height="323" /></a><figcaption>Specification Pattern in <a href="/wiki/Unified_Modeling_Language" title="Unified Modeling Language">UML</a> </figcaption></figure> In computer programming, the specification pattern is a particular <a href="/wiki/Software_design_pattern" title="Software design pattern">software design pattern</a>, whereby <a href="/wiki/Business_rules" class="mw-redirect" title="Business rules">business rules</a> can be recombined by chaining the business rules together using <a href="/wiki/Boolean_algebra" title="Boolean algebra">boolean logic</a>. The pattern is frequently used in the context of <a href="/wiki/Domain-driven_design" title="Domain-driven design">domain-driven design</a>. A specification pattern outlines a business rule that is combinable with other business rules. In this pattern, a unit of business logic inherits its functionality from the abstract aggregate Composite Specification class. The Composite Specification class has one function called IsSatisfiedBy that returns a boolean value. After instantiation, the specification is "chained" with other specifications, making new specifications easily maintainable, yet highly customizable business logic. Furthermore, upon instantiation the business logic may, through method invocation or <a href="/wiki/Inversion_of_control" title="Inversion of control">inversion of control</a>, have its state altered in order to become a delegate of other classes such as a persistence repository. As a consequence of performing runtime composition of high-level business/domain logic, the Specification pattern is a convenient tool for converting ad-hoc user search criteria into low level logic to be processed by repositories. Since a specification is an encapsulation of logic in a reusable form it is very simple to thoroughly unit test, and when used in this context is also an implementation of the humble object pattern. <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Code_examples">Code examples</h2>[<a href="/w/index.php?title=Specification_pattern&action=edit&section=1" title="Edit section: Code examples">edit</a>]</div> <div class="mw-heading mw-heading3"><h3 id="C#">C#</h3>[<a href="/w/index.php?title=Specification_pattern&action=edit&section=2" title="Edit section: C#">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/C_Sharp_(programming_language)" title="C Sharp (programming language)">C Sharp (programming language)</a></div> <div class="mw-highlight mw-highlight-lang-csharp mw-content-ltr" dir="ltr"><pre>public interface ISpecification { bool IsSatisfiedBy(object candidate); ISpecification And(ISpecification other); ISpecification AndNot(ISpecification other); ISpecification Or(ISpecification other); ISpecification OrNot(ISpecification other); ISpecification Not(); } public abstract class CompositeSpecification : ISpecification { public abstract bool IsSatisfiedBy(object candidate); public ISpecification And(ISpecification other) { return new AndSpecification(this, other); } public ISpecification AndNot(ISpecification other) { return new AndNotSpecification(this, other); } public ISpecification Or(ISpecification other) { return new OrSpecification(this, other); } public ISpecification OrNot(ISpecification other) { return new OrNotSpecification(this, other); } public ISpecification Not() { return new NotSpecification(this); } } public class AndSpecification : CompositeSpecification { private ISpecification leftCondition; private ISpecification rightCondition; public AndSpecification(ISpecification left, ISpecification right) { leftCondition = left; rightCondition = right; } public override bool IsSatisfiedBy(object candidate) { return leftCondition.IsSatisfiedBy(candidate) && rightCondition.IsSatisfiedBy(candidate); } } public class AndNotSpecification : CompositeSpecification { private ISpecification leftCondition; private ISpecification rightCondition; public AndNotSpecification(ISpecification left, ISpecification right) { leftCondition = left; rightCondition = right; } public override bool IsSatisfiedBy(object candidate) { return leftCondition.IsSatisfiedBy(candidate) && rightCondition.IsSatisfiedBy(candidate) != true; } } public class OrSpecification : CompositeSpecification { private ISpecification leftCondition; private ISpecification rightCondition; public OrSpecification(ISpecification left, ISpecification right) { leftCondition = left; rightCondition = right; } public override bool IsSatisfiedBy(object candidate) { return leftCondition.IsSatisfiedBy(candidate) || rightCondition.IsSatisfiedBy(candidate); } } public class OrNotSpecification : CompositeSpecification { private ISpecification leftCondition; private ISpecification rightCondition; public OrNotSpecification(ISpecification left, ISpecification right) { leftCondition = left; rightCondition = right; } public override bool IsSatisfiedBy(object candidate) { return leftCondition.IsSatisfiedBy(candidate) || rightCondition.IsSatisfiedBy(candidate) != true; } } public class NotSpecification : CompositeSpecification { private ISpecification Wrapped; public NotSpecification(ISpecification x) { Wrapped = x; } public override bool IsSatisfiedBy(object candidate) { return !Wrapped.IsSatisfiedBy(candidate); } } </pre></div> <div class="mw-heading mw-heading3"><h3 id="C#_6.0_with_generics">C# 6.0 with generics</h3>[<a href="/w/index.php?title=Specification_pattern&action=edit&section=3" title="Edit section: C# 6.0 with generics">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/C_Sharp_(programming_language)" title="C Sharp (programming language)">C Sharp (programming language)</a></div> <div class="mw-highlight mw-highlight-lang-csharp mw-content-ltr" dir="ltr"><pre>public interface ISpecification<T> { bool IsSatisfiedBy(T candidate); ISpecification<T> And(ISpecification<T> other); ISpecification<T> AndNot(ISpecification<T> other); ISpecification<T> Or(ISpecification<T> other); ISpecification<T> OrNot(ISpecification<T> other); ISpecification<T> Not(); } public abstract class LinqSpecification<T> : CompositeSpecification<T> { public abstract Expression<Func<T, bool>> AsExpression(); public override bool IsSatisfiedBy(T candidate) => AsExpression().Compile()(candidate); } public abstract class CompositeSpecification<T> : ISpecification<T> { public abstract bool IsSatisfiedBy(T candidate); public ISpecification<T> And(ISpecification<T> other) => new AndSpecification<T>(this, other); public ISpecification<T> AndNot(ISpecification<T> other) => new AndNotSpecification<T>(this, other); public ISpecification<T> Or(ISpecification<T> other) => new OrSpecification<T>(this, other); public ISpecification<T> OrNot(ISpecification<T> other) => new OrNotSpecification<T>(this, other); public ISpecification<T> Not() => new NotSpecification<T>(this); } public class AndSpecification<T> : CompositeSpecification<T> { ISpecification<T> left; ISpecification<T> right; public AndSpecification(ISpecification<T> left, ISpecification<T> right) { this.left = left; this.right = right; } public override bool IsSatisfiedBy(T candidate) => left.IsSatisfiedBy(candidate) && right.IsSatisfiedBy(candidate); } public class AndNotSpecification<T> : CompositeSpecification<T> { ISpecification<T> left; ISpecification<T> right; public AndNotSpecification(ISpecification<T> left, ISpecification<T> right) { this.left = left; this.right = right; } public override bool IsSatisfiedBy(T candidate) => left.IsSatisfiedBy(candidate) && !right.IsSatisfiedBy(candidate); } public class OrSpecification<T> : CompositeSpecification<T> { ISpecification<T> left; ISpecification<T> right; public OrSpecification(ISpecification<T> left, ISpecification<T> right) { this.left = left; this.right = right; } public override bool IsSatisfiedBy(T candidate) => left.IsSatisfiedBy(candidate) || right.IsSatisfiedBy(candidate); } public class OrNotSpecification<T> : CompositeSpecification<T> { ISpecification<T> left; ISpecification<T> right; public OrNotSpecification(ISpecification<T> left, ISpecification<T> right) { this.left = left; this.right = right; } public override bool IsSatisfiedBy(T candidate) => left.IsSatisfiedBy(candidate) || !right.IsSatisfiedBy(candidate); } public class NotSpecification<T> : CompositeSpecification<T> { ISpecification<T> other; public NotSpecification(ISpecification<T> other) => this.other = other; public override bool IsSatisfiedBy(T candidate) => !other.IsSatisfiedBy(candidate); } </pre></div> <div class="mw-heading mw-heading3"><h3 id="Python">Python</h3>[<a href="/w/index.php?title=Specification_pattern&action=edit&section=4" title="Edit section: Python">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Python_(programming_language)" title="Python (programming language)">Python (programming language)</a></div> <div class="mw-highlight mw-highlight-lang-python mw-content-ltr" dir="ltr"><pre>from abc import ABC, abstractmethod from dataclasses import dataclass from typing import Any class BaseSpecification(ABC): @abstractmethod def is_satisfied_by(self, candidate: Any) -> bool: raise NotImplementedError() def __call__(self, candidate: Any) -> bool: return self.is_satisfied_by(candidate) def __and__(self, other: "BaseSpecification") -> "AndSpecification": return AndSpecification(self, other) def __or__(self, other: "BaseSpecification") -> "OrSpecification": return OrSpecification(self, other) def __neg__(self) -> "NotSpecification": return NotSpecification(self) @dataclass(frozen=True) class AndSpecification(BaseSpecification): first: BaseSpecification second: BaseSpecification def is_satisfied_by(self, candidate: Any) -> bool: return self.first.is_satisfied_by(candidate) and self.second.is_satisfied_by(candidate) @dataclass(frozen=True) class OrSpecification(BaseSpecification): first: BaseSpecification second: BaseSpecification def is_satisfied_by(self, candidate: Any) -> bool: return self.first.is_satisfied_by(candidate) or self.second.is_satisfied_by(candidate) @dataclass(frozen=True) class NotSpecification(BaseSpecification): subject: BaseSpecification def is_satisfied_by(self, candidate: Any) -> bool: return not self.subject.is_satisfied_by(candidate) </pre></div> <div class="mw-heading mw-heading3"><h3 id="C++">C++</h3>[<a href="/w/index.php?title=Specification_pattern&action=edit&section=5" title="Edit section: C++">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/C%2B%2B" title="C++">C++</a></div> <div class="mw-highlight mw-highlight-lang-cpp mw-content-ltr" dir="ltr"><pre>template <class T> class ISpecification { public: virtual ~ISpecification() = default; virtual bool IsSatisfiedBy(T Candidate) const = 0; virtual ISpecification<T>* And(const ISpecification<T>& Other) const = 0; virtual ISpecification<T>* AndNot(const ISpecification<T>& Other) const = 0; virtual ISpecification<T>* Or(const ISpecification<T>& Other) const = 0; virtual ISpecification<T>* OrNot(const ISpecification<T>& Other) const = 0; virtual ISpecification<T>* Not() const = 0; }; template <class T> class CompositeSpecification : public ISpecification<T> { public: virtual bool IsSatisfiedBy(T Candidate) const override = 0; virtual ISpecification<T>* And(const ISpecification<T>& Other) const override; virtual ISpecification<T>* AndNot(const ISpecification<T>& Other) const override; virtual ISpecification<T>* Or(const ISpecification<T>& Other) const override; virtual ISpecification<T>* OrNot(const ISpecification<T>& Other) const override; virtual ISpecification<T>* Not() const override; }; template <class T> class AndSpecification final : public CompositeSpecification<T> { public: const ISpecification<T>& Left; const ISpecification<T>& Right; AndSpecification(const ISpecification<T>& InLeft, const ISpecification<T>& InRight) : Left(InLeft), Right(InRight) { } virtual bool IsSatisfiedBy(T Candidate) const override { return Left.IsSatisfiedBy(Candidate) && Right.IsSatisfiedBy(Candidate); } }; template <class T> ISpecification<T>* CompositeSpecification<T>::And(const ISpecification<T>& Other) const { return new AndSpecification<T>(*this, Other); } template <class T> class AndNotSpecification final : public CompositeSpecification<T> { public: const ISpecification<T>& Left; const ISpecification<T>& Right; AndNotSpecification(const ISpecification<T>& InLeft, const ISpecification<T>& InRight) : Left(InLeft), Right(InRight) { } virtual bool IsSatisfiedBy(T Candidate) const override { return Left.IsSatisfiedBy(Candidate) && !Right.IsSatisfiedBy(Candidate); } }; template <class T> class OrSpecification final : public CompositeSpecification<T> { public: const ISpecification<T>& Left; const ISpecification<T>& Right; OrSpecification(const ISpecification<T>& InLeft, const ISpecification<T>& InRight) : Left(InLeft), Right(InRight) { } virtual bool IsSatisfiedBy(T Candidate) const override { return Left.IsSatisfiedBy(Candidate) || Right.IsSatisfiedBy(Candidate); } }; template <class T> class OrNotSpecification final : public CompositeSpecification<T> { public: const ISpecification<T>& Left; const ISpecification<T>& Right; OrNotSpecification(const ISpecification<T>& InLeft, const ISpecification<T>& InRight) : Left(InLeft), Right(InRight) { } virtual bool IsSatisfiedBy(T Candidate) const override { return Left.IsSatisfiedBy(Candidate) || !Right.IsSatisfiedBy(Candidate); } }; template <class T> class NotSpecification final : public CompositeSpecification<T> { public: const ISpecification<T>& Other; NotSpecification(const ISpecification<T>& InOther) : Other(InOther) { } virtual bool IsSatisfiedBy(T Candidate) const override { return !Other.IsSatisfiedBy(Candidate); } }; template <class T> ISpecification<T>* CompositeSpecification<T>::AndNot(const ISpecification<T>& Other) const { return new AndNotSpecification<T>(*this, Other); } template <class T> ISpecification<T>* CompositeSpecification<T>::Or(const ISpecification<T>& Other) const { return new OrSpecification<T>(*this, Other); } template <class T> ISpecification<T>* CompositeSpecification<T>::OrNot(const ISpecification<T>& Other) const { return new OrNotSpecification<T>(*this, Other); } template <class T> ISpecification<T>* CompositeSpecification<T>::Not() const { return new NotSpecification<T>(*this); } </pre></div> <div class="mw-heading mw-heading3"><h3 id="TypeScript">TypeScript</h3>[<a href="/w/index.php?title=Specification_pattern&action=edit&section=6" title="Edit section: TypeScript">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/TypeScript" title="TypeScript">TypeScript</a></div> <div class="mw-highlight mw-highlight-lang-typescript mw-content-ltr" dir="ltr"><pre>export interface ISpecification { isSatisfiedBy(candidate: unknown): boolean; and(other: ISpecification): ISpecification; andNot(other: ISpecification): ISpecification; or(other: ISpecification): ISpecification; orNot(other: ISpecification): ISpecification; not(): ISpecification; } export abstract class CompositeSpecification implements ISpecification { abstract isSatisfiedBy(candidate: unknown): boolean; and(other: ISpecification): ISpecification { return new AndSpecification(this, other); } andNot(other: ISpecification): ISpecification { return new AndNotSpecification(this, other); } or(other: ISpecification): ISpecification { return new OrSpecification(this, other); } orNot(other: ISpecification): ISpecification { return new OrNotSpecification(this, other); } not(): ISpecification { return new NotSpecification(this); } } export class AndSpecification extends CompositeSpecification { constructor(private leftCondition: ISpecification, private rightCondition: ISpecification) { super(); } isSatisfiedBy(candidate: unknown): boolean { return this.leftCondition.isSatisfiedBy(candidate) && this.rightCondition.isSatisfiedBy(candidate); } } export class AndNotSpecification extends CompositeSpecification { constructor(private leftCondition: ISpecification, private rightCondition: ISpecification) { super(); } isSatisfiedBy(candidate: unknown): boolean { return this.leftCondition.isSatisfiedBy(candidate) && this.rightCondition.isSatisfiedBy(candidate) !== true; } } export class OrSpecification extends CompositeSpecification { constructor(private leftCondition: ISpecification, private rightCondition: ISpecification) { super(); } isSatisfiedBy(candidate: unknown): boolean { return this.leftCondition.isSatisfiedBy(candidate) || this.rightCondition.isSatisfiedBy(candidate); } } export class OrNotSpecification extends CompositeSpecification { constructor(private leftCondition: ISpecification, private rightCondition: ISpecification) { super(); } isSatisfiedBy(candidate: unknown): boolean { return this.leftCondition.isSatisfiedBy(candidate) || this.rightCondition.isSatisfiedBy(candidate) !== true; } } export class NotSpecification extends CompositeSpecification { constructor(private wrapped: ISpecification) { super(); } isSatisfiedBy(candidate: unknown): boolean { return !this.wrapped.isSatisfiedBy(candidate); } } </pre></div> <div class="mw-heading mw-heading2"><h2 id="Example_of_use">Example of use</h2>[<a href="/w/index.php?title=Specification_pattern&action=edit&section=7" title="Edit section: Example of use">edit</a>]</div> In the next example, invoices are retrieved and sent to a collection agency if: <ol><li>they are overdue,</li> <li>notices have been sent, and</li> <li>they are not already with the collection agency.</li></ol> This example is meant to show the result of how the logic is 'chained' together. This usage example assumes a previously defined <code>OverdueSpecification</code> class that is satisfied when an invoice's due date is 30 days or older, a <code>NoticeSentSpecification</code> class that is satisfied when three notices have been sent to the customer, and an <code>InCollectionSpecification</code> class that is satisfied when an invoice has already been sent to the collection agency. The implementation of these classes isn't important here. Using these three specifications, we created a new specification called <code>SendToCollection</code> which will be satisfied when an invoice is overdue, when notices have been sent to the customer, and are not already with the collection agency. <div class="mw-highlight mw-highlight-lang-csharp mw-content-ltr" dir="ltr"><pre>var overDue = new OverDueSpecification(); var noticeSent = new NoticeSentSpecification(); var inCollection = new InCollectionSpecification(); // Example of specification pattern logic chaining var sendToCollection = overDue.And(noticeSent).And(inCollection.Not()); var invoiceCollection = Service.GetInvoices(); foreach (var currentInvoice in invoiceCollection) { if (sendToCollection.IsSatisfiedBy(currentInvoice)) { currentInvoice.SendToCollection(); } } </pre></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2>[<a href="/w/index.php?title=Specification_pattern&action=edit&section=8" title="Edit section: References">edit</a>]</div> <ul><li><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFEvans2004" class="citation book cs1">Evans, Eric (2004). Domain Driven Design. Addison-Wesley. p. 224.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Domain+Driven+Design&rft.pages=224&rft.pub=Addison-Wesley&rft.date=2004&rft.aulast=Evans&rft.aufirst=Eric&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASpecification+pattern" class="Z3988"></li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2>[<a href="/w/index.php?title=Specification_pattern&action=edit&section=9" title="Edit section: External links">edit</a>]</div> <ul><li><a rel="nofollow" class="external text" href="http://www.martinfowler.com/apsupp/spec.pdf">Specifications</a> by Eric Evans and Martin Fowler</li> <li><a rel="nofollow" class="external text" href="http://www.mattberther.com/2005/03/25/the-specification-pattern-a-primer/">The Specification Pattern: A Primer</a> by Matt Berther</li> <li><a rel="nofollow" class="external text" href="http://www.codeproject.com/KB/architecture/SpecificationPart1.aspx">The Specification Pattern: A Four Part Introduction using VB.Net </a> by Richard Dalton</li> <li><a rel="nofollow" class="external text" href="https://github.com/mbrevda/SpecificationPattern">The Specification Pattern in PHP</a> by Moshe Brevda</li> <li><a rel="nofollow" class="external text" href="https://github.com/Happyr/Doctrine-Specification">Happyr Doctrine Specification in PHP</a> by Happyr</li> <li><a rel="nofollow" class="external text" href="https://github.com/neoneye/SpecificationPattern">The Specification Pattern in Swift</a> by Simon Strandgaard</li> <li><a rel="nofollow" class="external text" href="https://github.com/thiagodp/spec-pattern">The Specification Pattern in TypeScript and JavaScript</a> by Thiago Delgado Pinto</li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110724151447/http://www.dpdk.nl/opensource/specification-pattern-for-selection-on-lists">specification pattern in flash actionscript 3</a> by Rolf Vreijdenberger</li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}</style><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output .navbox-subgroup{background-color:#fdfdfd}.mw-parser-output .navbox-list{line-height:1.5em;border-color:#fdfdfd}.mw-parser-output .navbox-list-with-group{text-align:left;border-left-width:2px;border-left-style:solid}.mw-parser-output tr+tr>.navbox-abovebelow,.mw-parser-output tr+tr>.navbox-group,.mw-parser-output tr+tr>.navbox-image,.mw-parser-output tr+tr>.navbox-list{border-top:2px solid #fdfdfd}.mw-parser-output .navbox-title{background-color:#ccf}.mw-parser-output .navbox-abovebelow,.mw-parser-output .navbox-group,.mw-parser-output .navbox-subgroup .navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}</style></div><div role="navigation" class="navbox" aria-labelledby="Software_design_patterns225" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374" /><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Design_patterns" title="Template:Design patterns"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Design_patterns" title="Template talk:Design patterns"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Design_patterns" title="Special:EditPage/Template:Design patterns"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Software_design_patterns225" style="font-size:114%;margin:0 4em"><a href="/wiki/Software_design_pattern" title="Software design pattern">Software design patterns</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Design_Patterns" title="Design Patterns">Gang of Four patterns</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Creational_pattern" title="Creational pattern">Creational</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Abstract_factory_pattern" title="Abstract factory pattern">Abstract factory</a></li> <li><a href="/wiki/Builder_pattern" title="Builder pattern">Builder</a></li> <li><a href="/wiki/Factory_method_pattern" title="Factory method pattern">Factory method</a></li> <li><a href="/wiki/Prototype_pattern" title="Prototype pattern">Prototype</a></li> <li><a href="/wiki/Singleton_pattern" title="Singleton pattern">Singleton</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Structural_pattern" title="Structural pattern">Structural</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Adapter_pattern" title="Adapter pattern">Adapter</a></li> <li><a href="/wiki/Bridge_pattern" title="Bridge pattern">Bridge</a></li> <li><a href="/wiki/Composite_pattern" title="Composite pattern">Composite</a></li> <li><a href="/wiki/Decorator_pattern" title="Decorator pattern">Decorator</a></li> <li><a href="/wiki/Facade_pattern" title="Facade pattern">Facade</a></li> <li><a href="/wiki/Flyweight_pattern" title="Flyweight pattern">Flyweight</a></li> <li><a href="/wiki/Proxy_pattern" title="Proxy pattern">Proxy</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Behavioral_pattern" title="Behavioral pattern">Behavioral</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chain-of-responsibility_pattern" title="Chain-of-responsibility pattern">Chain of responsibility</a></li> <li><a href="/wiki/Command_pattern" title="Command pattern">Command</a></li> <li><a href="/wiki/Interpreter_pattern" title="Interpreter pattern">Interpreter</a></li> <li><a href="/wiki/Iterator_pattern" title="Iterator pattern">Iterator</a></li> <li><a href="/wiki/Mediator_pattern" title="Mediator pattern">Mediator</a></li> <li><a href="/wiki/Memento_pattern" title="Memento pattern">Memento</a></li> <li><a href="/wiki/Observer_pattern" title="Observer pattern">Observer</a></li> <li><a href="/wiki/State_pattern" title="State pattern">State</a></li> <li><a href="/wiki/Strategy_pattern" title="Strategy pattern">Strategy</a></li> <li><a href="/wiki/Template_method_pattern" title="Template method pattern">Template method</a></li> <li><a href="/wiki/Visitor_pattern" title="Visitor pattern">Visitor</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Concurrency_pattern" title="Concurrency pattern">Concurrency patterns</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Active_object" title="Active object">Active object</a></li> <li><a href="/wiki/Balking_pattern" title="Balking pattern">Balking</a></li> <li><a href="/wiki/Binding_properties_pattern" title="Binding properties pattern">Binding properties</a></li> <li><a href="/wiki/Double-checked_locking" title="Double-checked locking">Double-checked locking</a></li> <li><a href="/wiki/Asynchronous_method_invocation" title="Asynchronous method invocation">Event-based asynchronous</a></li> <li><a href="/wiki/Guarded_suspension" title="Guarded suspension">Guarded suspension</a></li> <li><a href="/wiki/Join-pattern" title="Join-pattern">Join</a></li> <li><a href="/wiki/Lock_(computer_science)" title="Lock (computer science)">Lock</a></li> <li><a href="/wiki/Monitor_(synchronization)" title="Monitor (synchronization)">Monitor</a></li> <li><a href="/wiki/Proactor_pattern" title="Proactor pattern">Proactor</a></li> <li><a href="/wiki/Reactor_pattern" title="Reactor pattern">Reactor</a></li> <li><a href="/wiki/Readers%E2%80%93writer_lock" title="Readers–writer lock">Read–write lock</a></li> <li><a href="/wiki/Scheduler_pattern" class="mw-redirect" title="Scheduler pattern">Scheduler</a></li> <li><a href="/wiki/Scheduled-task_pattern" title="Scheduled-task pattern">Scheduled-task pattern</a></li> <li><a href="/wiki/Semaphore_(programming)" title="Semaphore (programming)">Semaphore</a></li> <li><a href="/wiki/Thread_pool" title="Thread pool">Thread pool</a></li> <li><a href="/wiki/Thread-local_storage" title="Thread-local storage">Thread-local storage</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Architectural_pattern" title="Architectural pattern">Architectural patterns</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Front_controller" title="Front controller">Front controller</a></li> <li><a href="/wiki/Interceptor_pattern" title="Interceptor pattern">Interceptor</a></li> <li><a href="/wiki/Model%E2%80%93view%E2%80%93controller" title="Model–view–controller">MVC</a> <ul><li><a href="/wiki/Model%E2%80%93view%E2%80%93presenter" title="Model–view–presenter">MVP</a></li> <li><a href="/wiki/Model%E2%80%93view%E2%80%93viewmodel" title="Model–view–viewmodel">MVVM</a></li></ul></li> <li><a href="/wiki/Action%E2%80%93domain%E2%80%93responder" title="Action–domain–responder">ADR</a></li> <li><a href="/wiki/Entity_component_system" title="Entity component system">ECS</a></li> <li><a href="/wiki/Multitier_architecture" title="Multitier architecture">n-tier</a></li> <li><a class="mw-selflink selflink">Specification</a></li> <li><a href="/wiki/Publish%E2%80%93subscribe_pattern" title="Publish–subscribe pattern">Publish–subscribe</a></li> <li><a href="/wiki/Naked_objects" title="Naked objects">Naked objects</a></li> <li><a href="/wiki/Service_locator_pattern" title="Service locator pattern">Service locator</a></li> <li><a href="/wiki/Active_record_pattern" title="Active record pattern">Active record</a></li> <li><a href="/wiki/Identity_map_pattern" title="Identity map pattern">Identity map</a></li> <li><a href="/wiki/Data_access_object" title="Data access object">Data access object</a></li> <li><a href="/wiki/Data_transfer_object" title="Data transfer object">Data transfer object</a></li> <li><a href="/wiki/Inversion_of_control" title="Inversion of control">Inversion of control</a></li> <li><a href="/wiki/JSP_model_2_architecture" title="JSP model 2 architecture">Model 2</a></li> <li><a href="/wiki/Broker_pattern" title="Broker pattern">Broker</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other patterns</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Blackboard_design_pattern" class="mw-redirect" title="Blackboard design pattern">Blackboard</a></li> <li><a href="/wiki/Business_delegate_pattern" title="Business delegate pattern">Business delegate</a></li> <li><a href="/wiki/Composite_entity_pattern" title="Composite entity pattern">Composite entity</a></li> <li><a href="/wiki/Dependency_injection" title="Dependency injection">Dependency injection</a></li> <li><a href="/wiki/Intercepting_filter_pattern" title="Intercepting filter pattern">Intercepting filter</a></li> <li><a href="/wiki/Lazy_loading" title="Lazy loading">Lazy loading</a></li> <li><a href="/wiki/Mock_object" title="Mock object">Mock object</a></li> <li><a href="/wiki/Null_object_pattern" title="Null object pattern">Null object</a></li> <li><a href="/wiki/Object_pool_pattern" title="Object pool pattern">Object pool</a></li> <li><a href="/wiki/Servant_(design_pattern)" title="Servant (design pattern)">Servant</a></li> <li><a href="/wiki/Twin_pattern" title="Twin pattern">Twin</a></li> <li><a href="/wiki/Type_Tunnel_pattern" class="mw-redirect" title="Type Tunnel pattern">Type tunnel</a></li> <li><a href="/wiki/Method_chaining" title="Method chaining">Method chaining</a></li> <li><a href="/wiki/Delegation_pattern" title="Delegation pattern">Delegation</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Books</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Design_Patterns" title="Design Patterns">Design Patterns</a></li> <li><a href="/wiki/Enterprise_Integration_Patterns" title="Enterprise Integration Patterns">Enterprise Integration Patterns</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">People</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Christopher_Alexander" title="Christopher Alexander">Christopher Alexander</a></li> <li><a href="/wiki/Erich_Gamma" title="Erich Gamma">Erich Gamma</a></li> <li><a href="/wiki/Ralph_Johnson_(computer_scientist)" title="Ralph Johnson (computer scientist)">Ralph Johnson</a></li> <li><a href="/wiki/John_Vlissides" title="John Vlissides">John Vlissides</a></li> <li><a href="/wiki/Grady_Booch" title="Grady Booch">Grady Booch</a></li> <li><a href="/wiki/Kent_Beck" title="Kent Beck">Kent Beck</a></li> <li><a href="/wiki/Ward_Cunningham" title="Ward Cunningham">Ward Cunningham</a></li> <li><a href="/wiki/Martin_Fowler_(software_engineer)" title="Martin Fowler (software engineer)">Martin Fowler</a></li> <li><a href="/wiki/Robert_C._Martin" title="Robert C. Martin">Robert Martin</a></li> <li><a href="/wiki/Jim_Coplien" title="Jim Coplien">Jim Coplien</a></li> <li><a href="/wiki/Douglas_C._Schmidt" title="Douglas C. Schmidt">Douglas Schmidt</a></li> <li><a href="/wiki/Linda_Rising" title="Linda Rising">Linda Rising</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Communities</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/The_Hillside_Group" title="The Hillside Group">The Hillside Group</a></li> <li><a href="/wiki/Portland_Pattern_Repository" title="Portland Pattern Repository">Portland Pattern Repository</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">See also</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Anti-pattern" title="Anti-pattern">Anti-pattern</a></li> <li><a href="/wiki/Architectural_pattern" title="Architectural pattern">Architectural pattern</a></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Specification_pattern&oldid=1238065670">https://en.wikipedia.org/w/index.php?title=Specification_pattern&oldid=1238065670</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Architectural_pattern_(computer_science)" title="Category:Architectural pattern (computer science)">Architectural pattern (computer science)</a></li><li><a href="/wiki/Category:Software_design_patterns" title="Category:Software design patterns">Software design patterns</a></li><li><a href="/wiki/Category:Programming_language_comparisons" title="Category:Programming language comparisons">Programming language comparisons</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden categories: <ul><li><a href="/wiki/Category:Articles_with_short_description" title="Category:Articles with short description">Articles with short description</a></li><li><a href="/wiki/Category:Short_description_is_different_from_Wikidata" title="Category:Short description is different from Wikidata">Short description is different from Wikidata</a></li><li><a href="/wiki/Category:Articles_with_example_C_Sharp_code" title="Category:Articles with example C Sharp code">Articles with example C Sharp code</a></li><li><a href="/wiki/Category:Articles_with_example_C%2B%2B_code" title="Category:Articles with example C++ code">Articles with example C++ code</a></li><li><a href="/wiki/Category:Articles_with_example_JavaScript_code" title="Category:Articles with example JavaScript code">Articles with example JavaScript code</a></li><li><a href="/wiki/Category:Articles_with_example_Python_(programming_language)_code" title="Category:Articles with example Python (programming language) code">Articles with example Python (programming language) code</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 1 August 2024, at 23:00 (UTC).</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. By using this site, you agree to the <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Terms_of_Use" class="extiw" title="foundation:Special:MyLanguage/Policy:Terms of Use">Terms of Use</a> and <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy" class="extiw" title="foundation:Special:MyLanguage/Policy:Privacy policy">Privacy Policy</a>. Wikipedia® is a registered trademark of the <a rel="nofollow" class="external text" href="https://wikimediafoundation.org/">Wikimedia Foundation, Inc.</a>, a non-profit organization.</li> </ul> <ul id="footer-places"> <li id="footer-places-privacy"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy">Privacy policy</a></li> <li id="footer-places-about"><a href="/wiki/Wikipedia:About">About Wikipedia</a></li> <li id="footer-places-disclaimers"><a href="/wiki/Wikipedia:General_disclaimer">Disclaimers</a></li> <li id="footer-places-contact"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us">Contact Wikipedia</a></li> <li id="footer-places-wm-codeofconduct"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Universal_Code_of_Conduct">Code of Conduct</a></li> <li id="footer-places-developers"><a href="https://developer.wikimedia.org">Developers</a></li> <li id="footer-places-statslink"><a href="https://stats.wikimedia.org/#/en.wikipedia.org">Statistics</a></li> <li id="footer-places-cookiestatement"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Cookie_statement">Cookie statement</a></li> <li id="footer-places-mobileview"><a href="//en.m.wikipedia.org/w/index.php?title=Specification_pattern&mobileaction=toggle_view_mobile" class="noprint stopMobileRedirectToggle">Mobile view</a></li> </ul> <ul id="footer-icons" class="noprint"> <li id="footer-copyrightico"><a href="https://wikimediafoundation.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><picture><source media="(min-width: 500px)" srcset="/static/images/footer/wikimedia-button.svg" width="84" height="29"><img src="/static/images/footer/wikimedia.svg" width="25" height="25" alt="Wikimedia Foundation" lang="en" loading="lazy"></picture></a></li> <li id="footer-poweredbyico"><a href="https://www.mediawiki.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><picture><source media="(min-width: 500px)" srcset="/w/resources/assets/poweredby_mediawiki.svg" width="88" height="31"><img src="/w/resources/assets/mediawiki_compact.svg" alt="Powered by MediaWiki" lang="en" width="25" height="25" loading="lazy"></picture></a></li> </ul> </footer> </div> </div> </div> <div class="vector-header-container vector-sticky-header-container"> <div id="vector-sticky-header" class="vector-sticky-header"> <div class="vector-sticky-header-start"> <div class="vector-sticky-header-icon-start vector-button-flush-left vector-button-flush-right" aria-hidden="true"> <button class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-sticky-header-search-toggle" tabindex="-1" data-event-name="ui.vector-sticky-search-form.icon"> Search </button> </div> <div role="search" class="vector-search-box-vue vector-search-box-show-thumbnail vector-search-box"> <div class="vector-typeahead-search-container"> <div class="cdx-typeahead-search cdx-typeahead-search--show-thumbnail"> <form action="/w/index.php" id="vector-sticky-search-form" class="cdx-search-input cdx-search-input--has-end-button"> <div class="cdx-search-input__input-wrapper" data-search-loc="header-moved"> <div class="cdx-text-input cdx-text-input--has-start-icon"> <input class="cdx-text-input__input" type="search" name="search" placeholder="Search Wikipedia"> </div> <input type="hidden" name="title" value="Special:Search"> </div> <button class="cdx-button cdx-search-input__end-button">Search</button> </form> </div> </div> </div> <div class="vector-sticky-header-context-bar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-sticky-header-toc" class="vector-dropdown mw-portlet mw-portlet-sticky-header-toc vector-sticky-header-toc vector-button-flush-left" > <input type="checkbox" id="vector-sticky-header-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-sticky-header-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-sticky-header-toc-label" for="vector-sticky-header-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" > Toggle the table of contents </label> <div class="vector-dropdown-content"> <div id="vector-sticky-header-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <div class="vector-sticky-header-context-bar-primary" aria-hidden="true" >Specification pattern</div> </div> </div> <div class="vector-sticky-header-end" aria-hidden="true"> <div class="vector-sticky-header-icons"> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only" id="ca-talk-sticky-header" tabindex="-1" data-event-name="talk-sticky-header"> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only" id="ca-subject-sticky-header" tabindex="-1" data-event-name="subject-sticky-header"> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only" id="ca-history-sticky-header" tabindex="-1" data-event-name="history-sticky-header"> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only mw-watchlink" id="ca-watchstar-sticky-header" tabindex="-1" data-event-name="watch-sticky-header"> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only" id="ca-edit-sticky-header" tabindex="-1" data-event-name="wikitext-edit-sticky-header"> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only" id="ca-ve-edit-sticky-header" tabindex="-1" data-event-name="ve-edit-sticky-header"> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only" id="ca-viewsource-sticky-header" tabindex="-1" data-event-name="ve-edit-protected-sticky-header"> </a> </div> <div class="vector-sticky-header-buttons"> <button class="cdx-button cdx-button--weight-quiet mw-interlanguage-selector" id="p-lang-btn-sticky-header" tabindex="-1" data-event-name="ui.dropdown-p-lang-btn-sticky-header"> 4 languages </button> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive" id="ca-addsection-sticky-header" tabindex="-1" data-event-name="addsection-sticky-header"> Add topic </a> </div> <div class="vector-sticky-header-icon-end"> <div class="vector-user-links"> </div> </div> </div> </div> </div> <div class="mw-portlet mw-portlet-dock-bottom emptyPortlet" id="p-dock-bottom"> <ul> </ul> </div> <script>(RLQ=window.RLQ||[]).push(function(){mw.config.set({"wgHostname":"mw-web.eqiad.main-68bdfd6598-cvrbh","wgBackendResponseTime":218,"wgPageParseReport":{"limitreport":{"cputime":"0.350","walltime":"0.751","ppvisitednodes":{"value":422,"limit":1000000},"postexpandincludesize":{"value":26654,"limit":2097152},"templateargumentsize":{"value":337,"limit":2097152},"expansiondepth":{"value":8,"limit":100},"expensivefunctioncount":{"value":11,"limit":500},"unstrip-depth":{"value":0,"limit":20},"unstrip-size":{"value":110166,"limit":5000000},"entityaccesscount":{"value":0,"limit":400},"timingprofile":["100.00% 611.688 1 -total"," 16.84% 102.994 1 Template:Short_description"," 16.31% 99.754 1 Template:Design_patterns"," 16.19% 99.051 2 Template:Navbox"," 13.67% 83.641 1 Template:Cite_book"," 10.91% 66.719 2 Template:Pagetype"," 4.84% 29.595 5 Template:Further"," 4.10% 25.107 2 Template:Main_other"," 3.80% 23.254 1 Template:SDcat"," 0.33% 2.026 1 Template:Short_description/lowercasecheck"]},"scribunto":{"limitreport-timeusage":{"value":"0.191","limit":"10.000"},"limitreport-memusage":{"value":3384378,"limit":52428800}},"cachereport":{"origin":"mw-web.eqiad.main-8669bc5c8-62hkn","timestamp":"20250318161936","ttl":2592000,"transientcontent":false}}});});</script> <script type="application/ld+json">{"@context":"https:\/\/schema.org","@type":"Article","name":"Specification pattern","url":"https:\/\/en.wikipedia.org\/wiki\/Specification_pattern","sameAs":"http:\/\/www.wikidata.org\/entity\/Q7575013","mainEntity":"http:\/\/www.wikidata.org\/entity\/Q7575013","author":{"@type":"Organization","name":"Contributors to Wikimedia projects"},"publisher":{"@type":"Organization","name":"Wikimedia Foundation, Inc.","logo":{"@type":"ImageObject","url":"https:\/\/www.wikimedia.org\/static\/images\/wmf-hor-googpub.png"}},"datePublished":"2007-07-04T19:31:02Z","dateModified":"2024-08-01T23:00:52Z","image":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/4\/46\/Specification_UML.png","headline":"design pattern where business rules can be recombined by chaining them together using boolean logic, often used in domain-driven design"}</script> </body> </html>