noSuchMethod method - Object class - dart:core library

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Example:</p> <pre class="language-dart"><code class="language-dart">dynamic object = 1; object.add(42); // Statically allowed, run-time error </code></pre> <p>This invalid code will invoke the <code>noSuchMethod</code> method of the integer <code>1</code> with an <a href="../../dart-core/Invocation-class.html">Invocation</a> representing the <code>.add(42)</code> call and arguments (which then throws).</p> <p>Classes can override <a href="../../dart-core/Object/noSuchMethod.html">noSuchMethod</a> to provide custom behavior for such invalid dynamic invocations.</p> <p>A class with a non-default <a href="../../dart-core/Object/noSuchMethod.html">noSuchMethod</a> invocation can also omit implementations for members of its interface. Example:</p> <pre class="language-dart"><code class="language-dart">class MockList<T> implements List<T> { noSuchMethod(Invocation invocation) { log(invocation); super.noSuchMethod(invocation); // Will throw. } } void main() { MockList().add(42); } </code></pre> <p>This code has no compile-time warnings or errors even though the <code>MockList</code> class has no concrete implementation of any of the <code>List</code> interface methods. Calls to <code>List</code> methods are forwarded to <code>noSuchMethod</code>, so this code will <code>log</code> an invocation similar to <code>Invocation.method(#add, [42])</code> and then throw.</p> <p>If a value is returned from <code>noSuchMethod</code>, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.</p> <p>The default behavior is to throw a <a href="../../dart-core/NoSuchMethodError-class.html">NoSuchMethodError</a>.</p> </section> <section class="summary source-code" id="source"> <h2><span>Implementation</span></h2> <pre class="language-dart"><code class="language-dart">@pragma("vm:entry-point") @pragma("wasm:entry-point") external dynamic noSuchMethod(Invocation invocation);</code></pre> </section> </div>  <div id="dartdoc-sidebar-left" class="sidebar sidebar-offcanvas-left">  <header id="header-search-sidebar" class="hidden-l"> <form class="search-sidebar" role="search"> <input type="text" id="search-sidebar" autocomplete="off" disabled class="form-control typeahead" placeholder="Loading search..."> </form> </header> <ol class="breadcrumbs gt-separated dark hidden-l" id="sidebar-nav"> <li><a href="../../index.html">Dart</a></li> <li><a href="../../dart-core/dart-core-library.html">dart:core</a></li> <li><a href="../../dart-core/Object-class.html">Object</a></li> <li class="self-crumb">noSuchMethod method</li> </ol> <h5>Object class</h5> <div id="dartdoc-sidebar-left-content"></div> </div> <div id="dartdoc-sidebar-right" class="sidebar sidebar-offcanvas-right"> </div> </main> <footer> <span class="no-break"> Dart 3.5.4 </span> <span class="glue-footer"> <span class="no-break"> | <a href="https://dart.dev/terms" title="Terms of use">Terms</a> </span> <span class="no-break"> | <a href="https://policies.google.com/privacy" target="_blank" rel="noopener" title="Privacy policy" class="no-automatic-external">Privacy</a> </span> <span class="no-break"> | <a href="https://dart.dev/security" title="Security philosophy and practices">Security</a> </span> <div class="copyright" style="font-size: 0.9em; color: darkgrey; margin-top: 0.5em;"> Except as otherwise noted, this site is licensed under a <a style="color: darkgrey;" href="https://creativecommons.org/licenses/by/4.0/"> Creative Commons Attribution 4.0 International License</a> and code samples are licensed under the <a style="color: darkgrey;" href="https://opensource.org/licenses/BSD-3-Clause" class="no-automatic-external"> 3-Clause BSD License</a> </div> </span> </footer> <script src="../../static-assets/highlight.pack.js?v1"></script> <script src="../../static-assets/docs.dart.js"></script> <button aria-hidden="true" class="glue-footer__link glue-cookie-notification-bar-control"> Cookies management controls </button> <script src="https://www.gstatic.com/glue/cookienotificationbar/cookienotificationbar.min.js" data-glue-cookie-notification-bar-category="2B"> </script> </body> </html>

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noSuchMethod method - Object class - dart:core library - Dart API