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<li><a href="https://www.python.org/" title="The Python Programming Language">Python</a> » </li> <li><a href="../pep-0000/">PEP Index</a> » </li> <li>PEP 362</li> </ul> <button id="colour-scheme-cycler" onClick="setColourScheme(nextColourScheme())"> <svg aria-hidden="true" class="colour-scheme-icon-when-auto"><use href="#svg-sun-half"></use></svg> <svg aria-hidden="true" class="colour-scheme-icon-when-dark"><use href="#svg-moon"></use></svg> <svg aria-hidden="true" class="colour-scheme-icon-when-light"><use href="#svg-sun"></use></svg> Toggle light / dark / auto colour theme </button> </header> <article> <section id="pep-content"> <h1 class="page-title">PEP 362 – Function Signature Object</h1> <dl class="rfc2822 field-list simple"> <dt class="field-odd">Author:</dt> <dd class="field-odd">Brett Cannon <brett at python.org>, Jiwon Seo <seojiwon at gmail.com>, Yury Selivanov <yury at edgedb.com>, Larry Hastings <larry at hastings.org></dd> <dt class="field-even">Status:</dt> <dd class="field-even"><abbr title="Accepted and implementation complete, or no longer active">Final</abbr></dd> <dt class="field-odd">Type:</dt> <dd class="field-odd"><abbr title="Normative PEP with a new feature for Python, implementation change for CPython or interoperability standard for the ecosystem">Standards Track</abbr></dd> <dt class="field-even">Created:</dt> <dd class="field-even">21-Aug-2006</dd> <dt class="field-odd">Python-Version:</dt> <dd class="field-odd">3.3</dd> <dt class="field-even">Post-History:</dt> <dd class="field-even">04-Jun-2012</dd> <dt class="field-odd">Resolution:</dt> <dd class="field-odd"><a class="reference external" href="https://mail.python.org/pipermail/python-dev/2012-June/120682.html">Python-Dev message</a></dd> </dl> <hr class="docutils" /> <section id="contents"> <details><summary>Table of Contents</summary><ul class="simple"> <li><a class="reference internal" href="#abstract">Abstract</a></li> <li><a class="reference internal" href="#signature-object">Signature Object</a></li> <li><a class="reference internal" href="#parameter-object">Parameter Object</a></li> <li><a class="reference internal" href="#boundarguments-object">BoundArguments Object</a></li> <li><a class="reference internal" href="#implementation">Implementation</a></li> <li><a class="reference internal" href="#design-considerations">Design Considerations</a><ul> <li><a class="reference internal" href="#no-implicit-caching-of-signature-objects">No implicit caching of Signature objects</a></li> <li><a class="reference internal" href="#some-functions-may-not-be-introspectable">Some functions may not be introspectable</a></li> <li><a class="reference internal" href="#signature-and-parameter-equivalence">Signature and Parameter equivalence</a></li> </ul> </li> <li><a class="reference internal" href="#examples">Examples</a><ul> <li><a class="reference internal" href="#visualizing-callable-objects-signature">Visualizing Callable Objects’ Signature</a></li> <li><a class="reference internal" href="#annotation-checker">Annotation Checker</a></li> </ul> </li> <li><a class="reference internal" href="#acceptance">Acceptance</a></li> <li><a class="reference internal" href="#references">References</a></li> <li><a class="reference internal" href="#copyright">Copyright</a></li> </ul> </details></section> <section id="abstract"> <h2><a class="toc-backref" href="#abstract" role="doc-backlink">Abstract</a></h2> Python has always supported powerful introspection capabilities, including introspecting functions and methods (for the rest of this PEP, “function” refers to both functions and methods). By examining a function object you can fully reconstruct the function’s signature. Unfortunately this information is stored in an inconvenient manner, and is spread across a half-dozen deeply nested attributes. This PEP proposes a new representation for function signatures. The new representation contains all necessary information about a function and its parameters, and makes introspection easy and straightforward. However, this object does not replace the existing function metadata, which is used by Python itself to execute those functions. The new metadata object is intended solely to make function introspection easier for Python programmers. </section> <section id="signature-object"> <h2><a class="toc-backref" href="#signature-object" role="doc-backlink">Signature Object</a></h2> A Signature object represents the call signature of a function and its return annotation. For each parameter accepted by the function it stores a <a class="reference internal" href="#parameter-object">Parameter object</a> in its <code class="docutils literal notranslate">parameters</code> collection. A Signature object has the following public attributes and methods: <ul> <li><dl class="simple"> <dt>return_annotation : object</dt><dd>The “return” annotation for the function. If the function has no “return” annotation, this attribute is set to <code class="docutils literal notranslate">Signature.empty</code>.</dd> </dl> </li> <li><dl class="simple"> <dt>parameters : OrderedDict</dt><dd>An ordered mapping of parameters’ names to the corresponding Parameter objects.</dd> </dl> </li> <li><dl class="simple"> <dt>bind(*args, **kwargs) -> BoundArguments</dt><dd>Creates a mapping from positional and keyword arguments to parameters. Raises a <code class="docutils literal notranslate">TypeError</code> if the passed arguments do not match the signature.</dd> </dl> </li> <li><dl class="simple"> <dt>bind_partial(*args, **kwargs) -> BoundArguments</dt><dd>Works the same way as <code class="docutils literal notranslate">bind()</code>, but allows the omission of some required arguments (mimics <code class="docutils literal notranslate">functools.partial</code> behavior.) Raises a <code class="docutils literal notranslate">TypeError</code> if the passed arguments do not match the signature.</dd> </dl> </li> <li><dl> <dt>replace(parameters=<optional>, *, return_annotation=<optional>) -> Signature</dt><dd>Creates a new Signature instance based on the instance <code class="docutils literal notranslate">replace</code> was invoked on. It is possible to pass different <code class="docutils literal notranslate">parameters</code> and/or <code class="docutils literal notranslate">return_annotation</code> to override the corresponding properties of the base signature. To remove <code class="docutils literal notranslate">return_annotation</code> from the copied <code class="docutils literal notranslate">Signature</code>, pass in <code class="docutils literal notranslate">Signature.empty</code>.Note that the ‘=<optional>’ notation, means that the argument is optional. This notation applies to the rest of this PEP. </dd> </dl> </li> </ul> Signature objects are immutable. Use <code class="docutils literal notranslate">Signature.replace()</code> to make a modified copy: <div class="highlight-default notranslate"><div class="highlight"><pre>>>> def foo() -> None: ... pass >>> sig = signature(foo) >>> new_sig = sig.replace(return_annotation="new return annotation") >>> new_sig is not sig True >>> new_sig.return_annotation != sig.return_annotation True >>> new_sig.parameters == sig.parameters True >>> new_sig = new_sig.replace(return_annotation=new_sig.empty) >>> new_sig.return_annotation is Signature.empty True </pre></div> </div> There are two ways to instantiate a Signature class: <ul class="simple"> <li><dl class="simple"> <dt>Signature(parameters=<optional>, *, return_annotation=Signature.empty)</dt><dd>Default Signature constructor. Accepts an optional sequence of <code class="docutils literal notranslate">Parameter</code> objects, and an optional <code class="docutils literal notranslate">return_annotation</code>. Parameters sequence is validated to check that there are no parameters with duplicate names, and that the parameters are in the right order, i.e. positional-only first, then positional-or-keyword, etc.</dd> </dl> </li> <li><dl class="simple"> <dt>Signature.from_function(function)</dt><dd>Returns a Signature object reflecting the signature of the function passed in.</dd> </dl> </li> </ul> It’s possible to test Signatures for equality. Two signatures are equal when their parameters are equal, their positional and positional-only parameters appear in the same order, and they have equal return annotations. Changes to the Signature object, or to any of its data members, do not affect the function itself. Signature also implements <code class="docutils literal notranslate">__str__</code>: <div class="highlight-default notranslate"><div class="highlight"><pre>>>> str(Signature.from_function((lambda *args: None))) '(*args)' >>> str(Signature()) '()' </pre></div> </div> </section> <section id="parameter-object"> <h2><a class="toc-backref" href="#parameter-object" role="doc-backlink">Parameter Object</a></h2> Python’s expressive syntax means functions can accept many different kinds of parameters with many subtle semantic differences. We propose a rich Parameter object designed to represent any possible function parameter. A Parameter object has the following public attributes and methods: <ul> <li><dl class="simple"> <dt>name : str</dt><dd>The name of the parameter as a string. Must be a valid python identifier name (with the exception of <code class="docutils literal notranslate">POSITIONAL_ONLY</code> parameters, which can have it set to <code class="docutils literal notranslate">None</code>.)</dd> </dl> </li> <li><dl class="simple"> <dt>default : object</dt><dd>The default value for the parameter. If the parameter has no default value, this attribute is set to <code class="docutils literal notranslate">Parameter.empty</code>.</dd> </dl> </li> <li><dl class="simple"> <dt>annotation : object</dt><dd>The annotation for the parameter. If the parameter has no annotation, this attribute is set to <code class="docutils literal notranslate">Parameter.empty</code>.</dd> </dl> </li> <li><dl> <dt>kind</dt><dd>Describes how argument values are bound to the parameter. Possible values:<ul> <li><code class="docutils literal notranslate">Parameter.POSITIONAL_ONLY</code> - value must be supplied as a positional argument.Python has no explicit syntax for defining positional-only parameters, but many built-in and extension module functions (especially those that accept only one or two parameters) accept them. </li> <li><code class="docutils literal notranslate">Parameter.POSITIONAL_OR_KEYWORD</code> - value may be supplied as either a keyword or positional argument (this is the standard binding behaviour for functions implemented in Python.)</li> <li><code class="docutils literal notranslate">Parameter.KEYWORD_ONLY</code> - value must be supplied as a keyword argument. Keyword only parameters are those which appear after a “*” or “*args” entry in a Python function definition.</li> <li><code class="docutils literal notranslate">Parameter.VAR_POSITIONAL</code> - a tuple of positional arguments that aren’t bound to any other parameter. This corresponds to a “*args” parameter in a Python function definition.</li> <li><code class="docutils literal notranslate">Parameter.VAR_KEYWORD</code> - a dict of keyword arguments that aren’t bound to any other parameter. This corresponds to a “**kwargs” parameter in a Python function definition.</li> </ul> Always use <code class="docutils literal notranslate">Parameter.*</code> constants for setting and checking value of the <code class="docutils literal notranslate">kind</code> attribute. </dd> </dl> </li> <li><dl class="simple"> <dt>replace(*, name=<optional>, kind=<optional>, default=<optional>, annotation=<optional>) -> Parameter</dt><dd>Creates a new Parameter instance based on the instance <code class="docutils literal notranslate">replaced</code> was invoked on. To override a Parameter attribute, pass the corresponding argument. To remove an attribute from a <code class="docutils literal notranslate">Parameter</code>, pass <code class="docutils literal notranslate">Parameter.empty</code>.</dd> </dl> </li> </ul> Parameter constructor: <ul class="simple"> <li><dl class="simple"> <dt>Parameter(name, kind, *, annotation=Parameter.empty, default=Parameter.empty)</dt><dd>Instantiates a Parameter object. <code class="docutils literal notranslate">name</code> and <code class="docutils literal notranslate">kind</code> are required, while <code class="docutils literal notranslate">annotation</code> and <code class="docutils literal notranslate">default</code> are optional.</dd> </dl> </li> </ul> Two parameters are equal when they have equal names, kinds, defaults, and annotations. Parameter objects are immutable. Instead of modifying a Parameter object, you can use <code class="docutils literal notranslate">Parameter.replace()</code> to create a modified copy like so: <div class="highlight-default notranslate"><div class="highlight"><pre>>>> param = Parameter('foo', Parameter.KEYWORD_ONLY, default=42) >>> str(param) 'foo=42' >>> str(param.replace()) 'foo=42' >>> str(param.replace(default=Parameter.empty, annotation='spam')) "foo:'spam'" </pre></div> </div> </section> <section id="boundarguments-object"> <h2><a class="toc-backref" href="#boundarguments-object" role="doc-backlink">BoundArguments Object</a></h2> Result of a <code class="docutils literal notranslate">Signature.bind</code> call. Holds the mapping of arguments to the function’s parameters. Has the following public attributes: <ul class="simple"> <li><dl class="simple"> <dt>arguments : OrderedDict</dt><dd>An ordered, mutable mapping of parameters’ names to arguments’ values. Contains only explicitly bound arguments. Arguments for which <code class="docutils literal notranslate">bind()</code> relied on a default value are skipped.</dd> </dl> </li> <li><dl class="simple"> <dt>args : tuple</dt><dd>Tuple of positional arguments values. Dynamically computed from the ‘arguments’ attribute.</dd> </dl> </li> <li><dl class="simple"> <dt>kwargs : dict</dt><dd>Dict of keyword arguments values. Dynamically computed from the ‘arguments’ attribute.</dd> </dl> </li> </ul> The <code class="docutils literal notranslate">arguments</code> attribute should be used in conjunction with <code class="docutils literal notranslate">Signature.parameters</code> for any arguments processing purposes. <code class="docutils literal notranslate">args</code> and <code class="docutils literal notranslate">kwargs</code> properties can be used to invoke functions: <div class="highlight-default notranslate"><div class="highlight"><pre>def test(a, *, b): ... sig = signature(test) ba = sig.bind(10, b=20) test(*ba.args, **ba.kwargs) </pre></div> </div> Arguments which could be passed as part of either <code class="docutils literal notranslate">*args</code> or <code class="docutils literal notranslate">**kwargs</code> will be included only in the <code class="docutils literal notranslate">BoundArguments.args</code> attribute. Consider the following example: <div class="highlight-default notranslate"><div class="highlight"><pre>def test(a=1, b=2, c=3): pass sig = signature(test) ba = sig.bind(a=10, c=13) >>> ba.args (10,) >>> ba.kwargs: {'c': 13} </pre></div> </div> </section> <section id="implementation"> <h2><a class="toc-backref" href="#implementation" role="doc-backlink">Implementation</a></h2> The implementation adds a new function <code class="docutils literal notranslate">signature()</code> to the <code class="docutils literal notranslate">inspect</code> module. The function is the preferred way of getting a <code class="docutils literal notranslate">Signature</code> for a callable object. The function implements the following algorithm: <ul class="simple"> <li>If the object is not callable - raise a TypeError</li> <li>If the object has a <code class="docutils literal notranslate">__signature__</code> attribute and if it is not <code class="docutils literal notranslate">None</code> - return it</li> <li>If it has a <code class="docutils literal notranslate">__wrapped__</code> attribute, return <code class="docutils literal notranslate">signature(object.__wrapped__)</code></li> <li>If the object is an instance of <code class="docutils literal notranslate">FunctionType</code>, construct and return a new <code class="docutils literal notranslate">Signature</code> for it</li> <li>If the object is a bound method, construct and return a new <code class="docutils literal notranslate">Signature</code> object, with its first parameter (usually <code class="docutils literal notranslate">self</code> or <code class="docutils literal notranslate">cls</code>) removed. (<code class="docutils literal notranslate">classmethod</code> and <code class="docutils literal notranslate">staticmethod</code> are supported too. Since both are descriptors, the former returns a bound method, and the latter returns its wrapped function.)</li> <li>If the object is an instance of <code class="docutils literal notranslate">functools.partial</code>, construct a new <code class="docutils literal notranslate">Signature</code> from its <code class="docutils literal notranslate">partial.func</code> attribute, and account for already bound <code class="docutils literal notranslate">partial.args</code> and <code class="docutils literal notranslate">partial.kwargs</code></li> <li>If the object is a class or metaclass:<ul> <li>If the object’s type has a <code class="docutils literal notranslate">__call__</code> method defined in its MRO, return a Signature for it</li> <li>If the object has a <code class="docutils literal notranslate">__new__</code> method defined in its MRO, return a Signature object for it</li> <li>If the object has a <code class="docutils literal notranslate">__init__</code> method defined in its MRO, return a Signature object for it</li> </ul> </li> <li>Return <code class="docutils literal notranslate">signature(object.__call__)</code></li> </ul> Note that the <code class="docutils literal notranslate">Signature</code> object is created in a lazy manner, and is not automatically cached. However, the user can manually cache a Signature by storing it in the <code class="docutils literal notranslate">__signature__</code> attribute. An implementation for Python 3.3 can be found at <a class="footnote-reference brackets" href="#impl" id="id1">[1]</a>. The python issue tracking the patch is <a class="footnote-reference brackets" href="#issue" id="id2">[2]</a>. </section> <section id="design-considerations"> <h2><a class="toc-backref" href="#design-considerations" role="doc-backlink">Design Considerations</a></h2> <section id="no-implicit-caching-of-signature-objects"> <h3><a class="toc-backref" href="#no-implicit-caching-of-signature-objects" role="doc-backlink">No implicit caching of Signature objects</a></h3> The first PEP design had a provision for implicit caching of <code class="docutils literal notranslate">Signature</code> objects in the <code class="docutils literal notranslate">inspect.signature()</code> function. However, this has the following downsides: <ul class="simple"> <li>If the <code class="docutils literal notranslate">Signature</code> object is cached then any changes to the function it describes will not be reflected in it. However, If the caching is needed, it can be always done manually and explicitly</li> <li>It is better to reserve the <code class="docutils literal notranslate">__signature__</code> attribute for the cases when there is a need to explicitly set to a <code class="docutils literal notranslate">Signature</code> object that is different from the actual one</li> </ul> </section> <section id="some-functions-may-not-be-introspectable"> <h3><a class="toc-backref" href="#some-functions-may-not-be-introspectable" role="doc-backlink">Some functions may not be introspectable</a></h3> Some functions may not be introspectable in certain implementations of Python. For example, in CPython, built-in functions defined in C provide no metadata about their arguments. Adding support for them is out of scope for this PEP. </section> <section id="signature-and-parameter-equivalence"> <h3><a class="toc-backref" href="#signature-and-parameter-equivalence" role="doc-backlink">Signature and Parameter equivalence</a></h3> We assume that parameter names have semantic significance–two signatures are equal only when their corresponding parameters are equal and have the exact same names. Users who want looser equivalence tests, perhaps ignoring names of VAR_KEYWORD or VAR_POSITIONAL parameters, will need to implement those themselves. </section> </section> <section id="examples"> <h2><a class="toc-backref" href="#examples" role="doc-backlink">Examples</a></h2> <section id="visualizing-callable-objects-signature"> <h3><a class="toc-backref" href="#visualizing-callable-objects-signature" role="doc-backlink">Visualizing Callable Objects’ Signature</a></h3> Let’s define some classes and functions: <div class="highlight-default notranslate"><div class="highlight"><pre>from inspect import signature from functools import partial, wraps class FooMeta(type): def __new__(mcls, name, bases, dct, *, bar:bool=False): return super().__new__(mcls, name, bases, dct) def __init__(cls, name, bases, dct, **kwargs): return super().__init__(name, bases, dct) class Foo(metaclass=FooMeta): def __init__(self, spam:int=42): self.spam = spam def __call__(self, a, b, *, c) -> tuple: return a, b, c @classmethod def spam(cls, a): return a def shared_vars(*shared_args): """Decorator factory that defines shared variables that are passed to every invocation of the function""" def decorator(f): @wraps(f) def wrapper(*args, **kwargs): full_args = shared_args + args return f(*full_args, **kwargs) # Override signature sig = signature(f) sig = sig.replace(tuple(sig.parameters.values())[1:]) wrapper.__signature__ = sig return wrapper return decorator @shared_vars({}) def example(_state, a, b, c): return _state, a, b, c def format_signature(obj): return str(signature(obj)) </pre></div> </div> Now, in the python REPL: <div class="highlight-default notranslate"><div class="highlight"><pre>>>> format_signature(FooMeta) '(name, bases, dct, *, bar:bool=False)' >>> format_signature(Foo) '(spam:int=42)' >>> format_signature(Foo.__call__) '(self, a, b, *, c) -> tuple' >>> format_signature(Foo().__call__) '(a, b, *, c) -> tuple' >>> format_signature(Foo.spam) '(a)' >>> format_signature(partial(Foo().__call__, 1, c=3)) '(b, *, c=3) -> tuple' >>> format_signature(partial(partial(Foo().__call__, 1, c=3), 2, c=20)) '(*, c=20) -> tuple' >>> format_signature(example) '(a, b, c)' >>> format_signature(partial(example, 1, 2)) '(c)' >>> format_signature(partial(partial(example, 1, b=2), c=3)) '(b=2, c=3)' </pre></div> </div> </section> <section id="annotation-checker"> <h3><a class="toc-backref" href="#annotation-checker" role="doc-backlink">Annotation Checker</a></h3> <div class="highlight-default notranslate"><div class="highlight"><pre>import inspect import functools def checktypes(func): '''Decorator to verify arguments and return types Example: >>> @checktypes ... def test(a:int, b:str) -> int: ... return int(a * b) >>> test(10, '1') 1111111111 >>> test(10, 1) Traceback (most recent call last): ... ValueError: foo: wrong type of 'b' argument, 'str' expected, got 'int' ''' sig = inspect.signature(func) types = {} for param in sig.parameters.values(): # Iterate through function's parameters and build the list of # arguments types type_ = param.annotation if type_ is param.empty or not inspect.isclass(type_): # Missing annotation or not a type, skip it continue types[param.name] = type_ # If the argument has a type specified, let's check that its # default value (if present) conforms with the type. if param.default is not param.empty and not isinstance(param.default, type_): raise ValueError("{func}: wrong type of a default value for {arg!r}". \ format(func=func.__qualname__, arg=param.name)) def check_type(sig, arg_name, arg_type, arg_value): # Internal function that encapsulates arguments type checking if not isinstance(arg_value, arg_type): raise ValueError("{func}: wrong type of {arg!r} argument, " \ "{exp!r} expected, got {got!r}". \ format(func=func.__qualname__, arg=arg_name, exp=arg_type.__name__, got=type(arg_value).__name__)) @functools.wraps(func) def wrapper(*args, **kwargs): # Let's bind the arguments ba = sig.bind(*args, **kwargs) for arg_name, arg in ba.arguments.items(): # And iterate through the bound arguments try: type_ = types[arg_name] except KeyError: continue else: # OK, we have a type for the argument, lets get the corresponding # parameter description from the signature object param = sig.parameters[arg_name] if param.kind == param.VAR_POSITIONAL: # If this parameter is a variable-argument parameter, # then we need to check each of its values for value in arg: check_type(sig, arg_name, type_, value) elif param.kind == param.VAR_KEYWORD: # If this parameter is a variable-keyword-argument parameter: for subname, value in arg.items(): check_type(sig, arg_name + ':' + subname, type_, value) else: # And, finally, if this parameter a regular one: check_type(sig, arg_name, type_, arg) result = func(*ba.args, **ba.kwargs) # The last bit - let's check that the result is correct return_type = sig.return_annotation if (return_type is not sig._empty and isinstance(return_type, type) and not isinstance(result, return_type)): raise ValueError('{func}: wrong return type, {exp} expected, got {got}'. \ format(func=func.__qualname__, exp=return_type.__name__, got=type(result).__name__)) return result return wrapper </pre></div> </div> </section> </section> <section id="acceptance"> <h2><a class="toc-backref" href="#acceptance" role="doc-backlink">Acceptance</a></h2> <a class="pep reference internal" href="../pep-0362/" title="PEP 362 – Function Signature Object">PEP 362</a> was accepted by Guido, Friday, June 22, 2012 <a class="footnote-reference brackets" href="#accepted" id="id3">[3]</a> . The reference implementation was committed to trunk later that day. </section> <section id="references"> <h2><a class="toc-backref" href="#references" role="doc-backlink">References</a></h2> <aside class="footnote-list brackets"> <aside class="footnote brackets" id="impl" role="doc-footnote"> <dt class="label" id="impl">[<a href="#id1">1</a>]</dt> <dd>pep362 branch (<a class="reference external" href="https://bitbucket.org/1st1/cpython/overview">https://bitbucket.org/1st1/cpython/overview</a>)</aside> <aside class="footnote brackets" id="issue" role="doc-footnote"> <dt class="label" id="issue">[<a href="#id2">2</a>]</dt> <dd>issue 15008 (<a class="reference external" href="http://bugs.python.org/issue15008">http://bugs.python.org/issue15008</a>)</aside> <aside class="footnote brackets" id="accepted" role="doc-footnote"> <dt class="label" id="accepted">[<a href="#id3">3</a>]</dt> <dd>“A Desperate Plea For Introspection (aka: BDFAP Needed)” (<a class="reference external" href="https://mail.python.org/pipermail/python-dev/2012-June/120682.html">https://mail.python.org/pipermail/python-dev/2012-June/120682.html</a>)</aside> </aside> </section> <section id="copyright"> <h2><a class="toc-backref" href="#copyright" role="doc-backlink">Copyright</a></h2> This document has been placed in the public domain. </section> </section> <hr class="docutils" /> Source: <a class="reference external" href="https://github.com/python/peps/blob/main/peps/pep-0362.rst">https://github.com/python/peps/blob/main/peps/pep-0362.rst</a> Last modified: <a class="reference external" href="https://github.com/python/peps/commits/main/peps/pep-0362.rst">2023-09-09 17:39:29 GMT</a> </article> <nav id="pep-sidebar"> <h2>Contents</h2> <ul> <li><a class="reference internal" href="#abstract">Abstract</a></li> <li><a class="reference internal" href="#signature-object">Signature Object</a></li> <li><a class="reference internal" href="#parameter-object">Parameter Object</a></li> <li><a class="reference internal" href="#boundarguments-object">BoundArguments Object</a></li> <li><a class="reference internal" href="#implementation">Implementation</a></li> <li><a class="reference internal" href="#design-considerations">Design Considerations</a><ul> <li><a class="reference internal" href="#no-implicit-caching-of-signature-objects">No implicit caching of Signature objects</a></li> <li><a class="reference internal" href="#some-functions-may-not-be-introspectable">Some functions may not be introspectable</a></li> <li><a class="reference internal" href="#signature-and-parameter-equivalence">Signature and Parameter equivalence</a></li> </ul> </li> <li><a class="reference internal" href="#examples">Examples</a><ul> <li><a class="reference internal" href="#visualizing-callable-objects-signature">Visualizing Callable Objects’ Signature</a></li> <li><a class="reference internal" href="#annotation-checker">Annotation Checker</a></li> </ul> </li> <li><a class="reference internal" href="#acceptance">Acceptance</a></li> <li><a class="reference internal" href="#references">References</a></li> <li><a class="reference internal" href="#copyright">Copyright</a></li> </ul> <a id="source" href="https://github.com/python/peps/blob/main/peps/pep-0362.rst">Page Source (GitHub)</a> </nav> </section> <script src="../_static/colour_scheme.js"></script> <script src="../_static/wrap_tables.js"></script> <script src="../_static/sticky_banner.js"></script> </body> </html>