# `inspect` — Inspect live objects

Source code: Lib/inspect.py

The `inspect` module provides several useful functions to help get information about live objects such as modules, classes, methods, functions, tracebacks, frame objects, and code objects. For example, it can help you examine the contents of a class, retrieve the source code of a method, extract and format the argument list for a function, or get all the information you need to display a detailed traceback.

There are four main kinds of services provided by this module: type checking, getting source code, inspecting classes and functions, and examining the interpreter stack.

## Types and members

The `getmembers()` function retrieves the members of an object such as a class or module. The functions whose names begin with “is” are mainly provided as convenient choices for the second argument to `getmembers()`. They also help you determine when you can expect to find the following special attributes (see Import-related attributes on module objects for module attributes):

Type | Attribute | Description
--- | --- | ---
class | __doc__ | documentation string
| __name__ | name with which this class was defined
| __qualname__ | qualified name
| __module__ | name of module in which this class was defined
| __type_params__ | A tuple containing the type parameters of a generic class
method | __doc__ | documentation string
| __name__ | name with which this method was defined
| __qualname__ | qualified name
| __func__ | function object containing implementation of method
| __self__ | instance to which this method is bound, or `None`
| __module__ | name of module in which this method was defined
function | __doc__ | documentation string
| __name__ | name with which this function was defined
| __qualname__ | qualified name
| __code__ | code object containing compiled function bytecode
| __defaults__ | tuple of any default values for positional or keyword parameters
| __kwdefaults__ | mapping of any default values for keyword-only parameters
| __globals__ | global namespace in which this function was defined
| __builtins__ | builtins namespace
| __annotations__ | mapping of parameters names to annotations; `"return"` key is reserved for return annotations.
| __type_params__ | A tuple containing the type parameters of a generic function
| __module__ | name of module in which this function was defined
traceback | tb_frame | frame object at this level
| tb_lasti | index of last attempted instruction in bytecode
| tb_lineno | current line number in Python source code
| tb_next | next inner traceback object (called by this level)
frame | f_back | next outer frame object (this frame’s caller)
| f_builtins | builtins namespace seen by this frame
| f_code | code object being executed in this frame
| f_globals | global namespace seen by this frame
| f_lasti | index of last attempted instruction in bytecode
| f_lineno | current line number in Python source code
| f_locals | local namespace seen by this frame
| f_generator | returns the generator or coroutine object that owns this frame, or `None` if the frame is of a regular function
| f_trace | tracing function for this frame, or `None`
| f_trace_lines | indicate whether a tracing event is triggered for each source source line
| f_trace_opcodes | indicate whether per-opcode events are requested
| clear() | used to clear all references to local variables
code | co_argcount | number of arguments (not including keyword only arguments, * or ** args)
| co_code | string of raw compiled bytecode
| co_cellvars | tuple of names of cell variables (referenced by containing scopes)
| co_consts | tuple of constants used in the bytecode
| co_filename | name of file in which this code object was created
| co_firstlineno | number of first line in Python source code
| co_flags | bitmap of `CO_*` flags, read more here
| co_lnotab | encoded mapping of line numbers to bytecode indices
| co_freevars | tuple of names of free variables (referenced via a function’s closure)
| co_posonlyargcount | number of positional only arguments
| co_kwonlyargcount | number of keyword only arguments (not including ** arg)
| co_name | name with which this code object was defined
| co_qualname | fully qualified name with which this code object was defined
| co_names | tuple of names other than arguments and function locals
| co_nlocals | number of local variables
| co_stacksize | virtual machine stack space required
| co_varnames | tuple of names of arguments and local variables
| co_lines() | returns an iterator that yields successive bytecode ranges
| co_positions() | returns an iterator of source code positions for each bytecode instruction
| replace() | returns a copy of the code object with new values
generator | __name__ | name
| __qualname__ | qualified name
| gi_frame | frame
| gi_running | is the generator running?
| gi_suspended | is the generator suspended?
| gi_code | code
| gi_yieldfrom | object being iterated by `yield from`, or `None`
async generator | __name__ | name
| __qualname__ | qualified name
| ag_await | object being awaited on, or `None`
| ag_frame | frame
| ag_running | is the generator running?
| ag_suspended | is the generator suspended?
| ag_code | code
coroutine | __name__ | name
| __qualname__ | qualified name
| cr_await | object being awaited on, or `None`
| cr_frame | frame
| cr_running | is the coroutine running?
| cr_suspended | is the coroutine suspended?
| cr_code | code
| cr_origin | where coroutine was created, or `None`. See `sys.set_coroutine_origin_tracking_depth()`
builtin | __doc__ | documentation string
| __name__ | original name of this function or method
| __qualname__ | qualified name
| __self__ | instance to which a method is bound, or `None`

Changed in version 3.5: Add `__qualname__` and `gi_yieldfrom` attributes to generators.

The `__name__` attribute of generators is now set from the function name, instead of the code name, and it can now be modified.

Changed in version 3.7: Add `cr_origin` attribute to coroutines.

Changed in version 3.10: Add `__builtins__` attribute to functions.

Changed in version 3.11: Add `gi_suspended` attribute to generators.

Changed in version 3.11: Add `cr_suspended` attribute to coroutines.

Changed in version 3.12: Add `ag_suspended` attribute to async generators.

Changed in version 3.14: Add `f_generator` attribute to frames.

inspect.getmembers(object[, predicate])

  Return all the members of an object in a list of `(name, value)` pairs sorted by name. If the optional predicate argument—which will be called with the `value` object of each member—is supplied, only members for which the predicate returns a true value are included.

  Note

  `getmembers()` will only return class attributes defined in the metaclass when the argument is a class and those attributes have been listed in the metaclass’ custom `__dir__()`.

inspect.getmembers_static(object[, predicate])

  Return all the members of an object in a list of `(name, value)` pairs sorted by name without triggering dynamic lookup via the descriptor protocol, __getattr__ or __getattribute__. Optionally, only return members that satisfy a given predicate.

  Note

  `getmembers_static()` may not be able to retrieve all members that getmembers can fetch (like dynamically created attributes) and may find members that getmembers can’t (like descriptors that raise AttributeError). It can also return descriptor objects instead of instance members in some cases.

  Added in version 3.11.

inspect.getmodulename(path)

  Return the name of the module named by the file path, without including the names of enclosing packages. The file extension is checked against all of the entries in `importlib.machinery.all_suffixes()`. If it matches, the final path component is returned with the extension removed. Otherwise, `None` is returned.

  Note that this function only returns a meaningful name for actual Python modules - paths that potentially refer to Python packages will still return `None`.

  Changed in version 3.3: The function is based directly on `importlib`.

inspect.ismodule(object)

  Return `True` if the object is a module.

inspect.isclass(object)

  Return `True` if the object is a class, whether built-in or created in Python code.

  This function returns `False` for generic aliases of classes, such as `list[int]`.

inspect.ismethod(object)

  Return `True` if the object is a bound method written in Python.

  Note

  For example, given this class:

      >>> class Greeter:
      ...     def say_hello(self):
      ...         print('hello!')

  A bound method (also known as an instance method) is created when accessing `say_hello` (a function defined in the `Greeter` namespace) through an instance of the `Greeter` class:

      >>> instance = Greeter()

      >>> instance.say_hello
      <bound method Greeter.say_hello of <__main__.Greeter object ...>>
      >>> ismethod(instance.say_hello)
      True
      >>> isfunction(instance.say_hello)
      False

  Accessing `say_hello` through the `Greeter` class will return the function itself. For this function, `ismethod()` will return `False`, but `isfunction()` will return `True`:

      >>> Greeter.say_hello
      <function Greeter.say_hello at 0x7f7503854a90>
      >>> ismethod(Greeter.say_hello)
      False
      >>> isfunction(Greeter.say_hello)
      True

  See Methods for details.

inspect.isfunction(object)

  Return `True` if the object is a Python function, which includes functions created by a lambda expression.

  See the note for `ismethod()` for an example.

inspect.ispackage(object)

  Return `True` if the object is a package.

  Added in version 3.14.

inspect.isgeneratorfunction(object)

  Return `True` if the object is a Python generator function.

  It also returns `True` for bound methods created from Python generator functions (see Methods for more information).

  Changed in version 3.8: Functions wrapped in `functools.partial()` now return `True` if the wrapped function is a Python generator function.

  Changed in version 3.13: Functions wrapped in `functools.partialmethod()` now return `True` if the wrapped function is a Python generator function.

inspect.isgenerator(object)

  Return `True` if the object is a generator.

inspect.iscoroutinefunction(object)

  Return `True` if the object is a coroutine function (a function defined with an `async def` syntax), a `functools.partial()` wrapping a coroutine function, or a sync function marked with `markcoroutinefunction()`.

  Added in version 3.5.

  Changed in version 3.8: Functions wrapped in `functools.partial()` now return `True` if the wrapped function is a coroutine function.

  Changed in version 3.12: Sync functions marked with `markcoroutinefunction()` now return `True`.

  Changed in version 3.13: Functions wrapped in `functools.partialmethod()` now return `True` if the wrapped function is a coroutine function.

inspect.markcoroutinefunction(func)

  Decorator to mark a callable as a coroutine function if it would not otherwise be detected by `iscoroutinefunction()`.

  This may be of use for sync functions that return a coroutine, if the function is passed to an API that requires `iscoroutinefunction()`.

  When possible, using an `async def` function is preferred. Also acceptable is calling the function and testing the return with `iscoroutine()`.

  Added in version 3.12.

inspect.iscoroutine(object)

  Return `True` if the object is a coroutine created by an `async def` function.

  Added in version 3.5.

inspect.isawaitable(object)

  Return `True` if the object can be used in `await` expression.

  Can also be used to distinguish generator-based coroutines from regular generators:

      import types

      def gen():
          yield
      @types.coroutine
      def gen_coro():
          yield

      assert not isawaitable(gen())
      assert isawaitable(gen_coro())

  Added in version 3.5.

inspect.isasyncgenfunction(object)

  Return `True` if the object is an asynchronous generator function, for example:

      >>> async def agen():
      ...     yield 1
      ...
      >>> inspect.isasyncgenfunction(agen)
      True

  Added in version 3.6.

  Changed in version 3.8: Functions wrapped in `functools.partial()` now return `True` if the wrapped function is an asynchronous generator function.

  Changed in version 3.13: Functions wrapped in `functools.partialmethod()` now return `True` if the wrapped function is a asynchronous generator function.

inspect.isasyncgen(object)

  Return `True` if the object is an asynchronous generator iterator created by an asynchronous generator function.

  Added in version 3.6.

inspect.istraceback(object)

  Return `True` if the object is a traceback.

inspect.isframe(object)

  Return `True` if the object is a frame.

inspect.iscode(object)

  Return `True` if the object is a code.

inspect.isbuiltin(object)

  Return `True` if the object is a built-in function or a bound built-in method.

inspect.ismethodwrapper(object)

  Return `True` if the type of object is a `MethodWrapperType`.

  These are instances of `MethodWrapperType`, such as `__str__()`, `__eq__()` and `__repr__()`.

  Added in version 3.11.

inspect.isroutine(object)

  Return `True` if the object is a user-defined or built-in function or method.

inspect.isabstract(object)

  Return `True` if the object is an abstract base class.

inspect.ismethoddescriptor(object)

  Return `True` if the object is a method descriptor, but not if `ismethod()`, `isclass()`, `isfunction()` or `isbuiltin()` are true.

  This, for example, is true of `int.__add__`. An object passing this test has a `__get__()` method, but not a `__set__()` method or a `__delete__()` method. Beyond that, the set of attributes varies. A `__name__` attribute is usually sensible, and `__doc__` often is.

  Methods implemented via descriptors that also pass one of the other tests return `False` from the `ismethoddescriptor()` test, simply because the other tests promise more – you can, e.g., count on having the `__func__` attribute (etc) when an object passes `ismethod()`.

  Changed in version 3.13: This function no longer incorrectly reports objects with `__get__()` and `__delete__()`, but not `__set__()`, as being method descriptors (such objects are data descriptors, not method descriptors).

inspect.isdatadescriptor(object)

  Return `True` if the object is a data descriptor.

  Data descriptors have a `__set__` or a `__delete__` method. Examples are properties (defined in Python), getsets, and members. The latter two are defined in C and there are more specific tests available for those types, which is robust across Python implementations. Typically, data descriptors will also have `__name__` and `__doc__` attributes (properties, getsets, and members have both of these attributes), but this is not guaranteed.

inspect.isgetsetdescriptor(object)

  Return `True` if the object is a getset descriptor.

  CPython implementation detail: getsets are attributes defined in extension modules via `PyGetSetDef` structures. For Python implementations without such types, this method will always return `False`.

inspect.ismemberdescriptor(object)

  Return `True` if the object is a member descriptor.

  CPython implementation detail: Member descriptors are attributes defined in extension modules via `PyMemberDef` structures. For Python implementations without such types, this method will always return `False`.

## Retrieving source code

inspect.getdoc(object)

  Get the documentation string for an object, cleaned up with `cleandoc()`. If the documentation string for an object is not provided and the object is a class, a method, a property or a descriptor, retrieve the documentation string from the inheritance hierarchy. Return `None` if the documentation string is invalid or missing.

  Changed in version 3.5: Documentation strings are now inherited if not overridden.

inspect.getcomments(object)

  Return in a single string any lines of comments immediately preceding the object’s source code (for a class, function, or method), or at the top of the Python source file (if the object is a module). If the object’s source code is unavailable, return `None`. This could happen if the object has been defined in C or the interactive shell.

inspect.getfile(object)

  Return the name of the (text or binary) file in which an object was defined. This will fail with a `TypeError` if the object is a built-in module, class, or function.

inspect.getmodule(object)

  Try to guess which module an object was defined in. Return `None` if the module cannot be determined.

inspect.getsourcefile(object)

  Return the name of the Python source file in which an object was defined or `None` if no way can be identified to get the source. This will fail with a `TypeError` if the object is a built-in module, class, or function.

inspect.getsourcelines(object)

  Return a list of source lines and starting line number for an object. The argument may be a module, class, method, function, traceback, frame, or code object. The source code is returned as a list of the lines corresponding to the object and the line number indicates where in the original source file the first line of code was found. An `OSError` is raised if the source code cannot be retrieved. A `TypeError` is raised if the object is a built-in module, class, or function.

  Changed in version 3.3: `OSError` is raised instead of `IOError`, now an alias of the former.

inspect.getsource(object)

  Return the text of the source code for an object. The argument may be a module, class, method, function, traceback, frame, or code object. The source code is returned as a single string. An `OSError` is raised if the source code cannot be retrieved. A `TypeError` is raised if the object is a built-in module, class, or function.

  Changed in version 3.3: `OSError` is raised instead of `IOError`, now an alias of the former.

inspect.cleandoc(doc)

  Clean up indentation from docstrings that are indented to line up with blocks of code.

  All leading whitespace is removed from the first line. Any leading whitespace that can be uniformly removed from the second line onwards is removed. Empty lines at the beginning and end are subsequently removed. Also, all tabs are expanded to spaces.

## Introspecting callables with the Signature object

Added in version 3.3.

The `Signature` object represents the call signature of a callable object and its return annotation. To retrieve a `Signature` object, use the `signature()` function.

inspect.signature(callable, *, follow_wrapped=True, globals=None, locals=None, eval_str=False, annotation_format=Format.VALUE)

  Return a `Signature` object for the given callable:

      >>> from inspect import signature
      >>> def foo(a, *, b:int, **kwargs):
      ...     pass

      >>> sig = signature(foo)

      >>> str(sig)
      '(a, *, b: int, **kwargs)'

      >>> str(sig.parameters['b'])
      'b: int'

      >>> sig.parameters['b'].annotation
      <class 'int'>

  Accepts a wide range of Python callables, from plain functions and classes to `functools.partial()` objects.

  If some of the annotations are strings (e.g., because `from __future__ import annotations` was used), `signature()` will attempt to automatically un-stringize the annotations using `annotationlib.get_annotations()`. The globals, locals, and eval_str parameters are passed into `annotationlib.get_annotations()` when resolving the annotations; see the documentation for `annotationlib.get_annotations()` for instructions on how to use these parameters. A member of the `annotationlib.Format` enum can be passed to the annotation_format parameter to control the format of the returned annotations. For example, use `annotation_format=annotationlib.Format.STRING` to return annotations in string format.

  Raises `ValueError` if no signature can be provided, and `TypeError` if that type of object is not supported. Also, if the annotations are stringized, and eval_str is not false, the `eval()` call(s) to un-stringize the annotations in `annotationlib.get_annotations()` could potentially raise any kind of exception.

  A slash (/) in the signature of a function denotes that the parameters prior to it are positional-only. For more info, see the FAQ entry on positional-only parameters.

  Changed in version 3.5: The follow_wrapped parameter was added. Pass `False` to get a signature of callable specifically (`callable.__wrapped__` will not be used to unwrap decorated callables.)

  Changed in version 3.10: The globals, locals, and eval_str parameters were added.

  Changed in version 3.14: The annotation_format parameter was added.

  Note

  Some callables may not be introspectable in certain implementations of Python. For example, in CPython, some built-in functions defined in C provide no metadata about their arguments.

  CPython implementation detail: If the passed object has a `__signature__` attribute, we may use it to create the signature. The exact semantics are an implementation detail and are subject to unannounced changes. Consult the source code for current semantics.

class inspect.Signature(parameters=None, *, return_annotation=Signature.empty)

  A `Signature` object represents the call signature of a function and its return annotation. For each parameter accepted by the function it stores a `Parameter` object in its `parameters` collection.

  The optional parameters argument is a sequence of `Parameter` objects, which 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, and that parameters with defaults follow parameters without defaults.

  The optional return_annotation argument can be an arbitrary Python object. It represents the “return” annotation of the callable.

  `Signature` objects are immutable. Use `Signature.replace()` or `copy.replace()` to make a modified copy.

  Changed in version 3.5: `Signature` objects are now picklable and hashable.

  empty

    A special class-level marker to specify absence of a return annotation.

  parameters

    An ordered mapping of parameters’ names to the corresponding `Parameter` objects. Parameters appear in strict definition order, including keyword-only parameters.

    Changed in version 3.7: Python only explicitly guaranteed that it preserved the declaration order of keyword-only parameters as of version 3.7, although in practice this order had always been preserved in Python 3.

  return_annotation

    The “return” annotation for the callable. If the callable has no “return” annotation, this attribute is set to `Signature.empty`.

  bind(*args, **kwargs)

    Create a mapping from positional and keyword arguments to parameters. Returns `BoundArguments` if `*args` and `**kwargs` match the signature, or raises a `TypeError`.

  bind_partial(*args, **kwargs)

    Works the same way as `Signature.bind()`, but allows the omission of some required arguments (mimics `functools.partial()` behavior.) Returns `BoundArguments`, or raises a `TypeError` if the passed arguments do not match the signature.

  replace(*[, parameters][, return_annotation])

    Create a new `Signature` instance based on the instance `replace()` was invoked on. It is possible to pass different parameters and/or return_annotation to override the corresponding properties of the base signature. To remove `return_annotation` from the copied `Signature`, pass in `Signature.empty`.

        >>> def test(a, b):
        ...     pass
        ...
        >>> sig = signature(test)
        >>> new_sig = sig.replace(return_annotation="new return anno")
        >>> str(new_sig)
        "(a, b) -> 'new return anno'"

    `Signature` objects are also supported by the generic function `copy.replace()`.

  format(*, max_width=None, quote_annotation_strings=True)

    Create a string representation of the `Signature` object.

    If max_width is passed, the method will attempt to fit the signature into lines of at most max_width characters. If the signature is longer than max_width, all parameters will be on separate lines.

    If quote_annotation_strings is False, annotations in the signature are displayed without opening and closing quotation marks if they are strings. This is useful if the signature was created with the `STRING` format or if `from __future__ import annotations` was used.

    Added in version 3.13.

    Changed in version 3.14: The unquote_annotations parameter was added.

  classmethod from_callable(obj, *, follow_wrapped=True, globals=None, locals=None, eval_str=False)

    Return a `Signature` (or its subclass) object for a given callable obj.

    This method simplifies subclassing of `Signature`:

        class MySignature(Signature):
            pass
        sig = MySignature.from_callable(sum)
        assert isinstance(sig, MySignature)

    Its behavior is otherwise identical to that of `signature()`.

    Added in version 3.5.

    Changed in version 3.10: The globals, locals, and eval_str parameters were added.

class inspect.Parameter(name, kind, *, default=Parameter.empty, annotation=Parameter.empty)

  `Parameter` objects are immutable. Instead of modifying a `Parameter` object, you can use `Parameter.replace()` or `copy.replace()` to create a modified copy.

  Changed in version 3.5: Parameter objects are now picklable and hashable.

  empty

    A special class-level marker to specify absence of default values and annotations.

  name

    The name of the parameter as a string. The name must be a valid Python identifier.

    CPython implementation detail: CPython generates implicit parameter names of the form `.0` on the code objects used to implement comprehensions and generator expressions.

    Changed in version 3.6: These parameter names are now exposed by this module as names like `implicit0`.

  default

    The default value for the parameter. If the parameter has no default value, this attribute is set to `Parameter.empty`.

  annotation

    The annotation for the parameter. If the parameter has no annotation, this attribute is set to `Parameter.empty`.

  kind

    Describes how argument values are bound to the parameter. The possible values are accessible via `Parameter` (like `Parameter.KEYWORD_ONLY`), and support comparison and ordering, in the following order:

    Name | Meaning
    --- | ---
    POSITIONAL_ONLY | Value must be supplied as a positional argument. Positional only parameters are those which appear before a `/` entry (if present) in a Python function definition.
    POSITIONAL_OR_KEYWORD | Value may be supplied as either a keyword or positional argument (this is the standard binding behaviour for functions implemented in Python.)
    VAR_POSITIONAL | A tuple of positional arguments that aren’t bound to any other parameter. This corresponds to a `*args` parameter in a Python function definition.
    KEYWORD_ONLY | 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.
    VAR_KEYWORD | A dict of keyword arguments that aren’t bound to any other parameter. This corresponds to a `**kwargs` parameter in a Python function definition.

    Example: print all keyword-only arguments without default values:

        >>> def foo(a, b, *, c, d=10):
        ...     pass

        >>> sig = signature(foo)
        >>> for param in sig.parameters.values():
        ...     if (param.kind == param.KEYWORD_ONLY and
        ...                        param.default is param.empty):
        ...         print('Parameter:', param)
        Parameter: c

  kind.description

    Describes an enum value of `Parameter.kind`.

    Added in version 3.8.

    Example: print all descriptions of arguments:

        >>> def foo(a, b, *, c, d=10):
        ...     pass

        >>> sig = signature(foo)
        >>> for param in sig.parameters.values():
        ...     print(param.kind.description)
        positional or keyword
        positional or keyword
        keyword-only
        keyword-only

  replace(*[, name][, kind][, default][, annotation])

    Create a new `Parameter` instance based on the instance replaced was invoked on. To override a `Parameter` attribute, pass the corresponding argument. To remove a default value or/and an annotation from a `Parameter`, pass `Parameter.empty`.

        >>> from inspect import Parameter
        >>> param = Parameter('foo', Parameter.KEYWORD_ONLY, default=42)
        >>> str(param)
        'foo=42'

        >>> str(param.replace()) # Will create a shallow copy of 'param'
        'foo=42'

        >>> str(param.replace(default=Parameter.empty, annotation='spam'))
        "foo: 'spam'"

    `Parameter` objects are also supported by the generic function `copy.replace()`.

  Changed in version 3.4: In Python 3.3 `Parameter` objects were allowed to have `name` set to `None` if their `kind` was set to `POSITIONAL_ONLY`. This is no longer permitted.

class inspect.BoundArguments

  Result of a `Signature.bind()` or `Signature.bind_partial()` call. Holds the mapping of arguments to the function’s parameters.

  arguments

    A mutable mapping of parameters’ names to arguments’ values. Contains only explicitly bound arguments. Changes in `arguments` will reflect in `args` and `kwargs`.

    Should be used in conjunction with `Signature.parameters` for any argument processing purposes.

    Note

    Arguments for which `Signature.bind()` or `Signature.bind_partial()` relied on a default value are skipped. However, if needed, use `BoundArguments.apply_defaults()` to add them.

    Changed in version 3.9: `arguments` is now of type `dict`. Formerly, it was of type `collections.OrderedDict`.

  args

    A tuple of positional arguments values. Dynamically computed from the `arguments` attribute.

  kwargs

    A dict of keyword arguments values. Dynamically computed from the `arguments` attribute. Arguments that can be passed positionally are included in `args` instead.

  signature

    A reference to the parent `Signature` object.

  apply_defaults()

    Set default values for missing arguments.

    For variable-positional arguments (`*args`) the default is an empty tuple.

    For variable-keyword arguments (`**kwargs`) the default is an empty dict.

        >>> def foo(a, b='ham', *args): pass
        >>> ba = inspect.signature(foo).bind('spam')
        >>> ba.apply_defaults()
        >>> ba.arguments
        {'a': 'spam', 'b': 'ham', 'args': ()}

    Added in version 3.5.

  The `args` and `kwargs` properties can be used to invoke functions:

      def test(a, *, b):
          ...

      sig = signature(test)
      ba = sig.bind(10, b=20)
      test(*ba.args, **ba.kwargs)

See also

PEP 362 - Function Signature Object.

  The detailed specification, implementation details and examples.

## Classes and functions

inspect.getclasstree(classes, unique=False)

  Arrange the given list of classes into a hierarchy of nested lists. Where a nested list appears, it contains classes derived from the class whose entry immediately precedes the list. Each entry is a 2-tuple containing a class and a tuple of its base classes. If the unique argument is true, exactly one entry appears in the returned structure for each class in the given list. Otherwise, classes using multiple inheritance and their descendants will appear multiple times.

inspect.getfullargspec(func)

  Get the names and default values of a Python function’s parameters. A named tuple is returned:

  `FullArgSpec(args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, annotations)`

  args is a list of the positional parameter names. varargs is the name of the `*` parameter or `None` if arbitrary positional arguments are not accepted. varkw is the name of the `**` parameter or `None` if arbitrary keyword arguments are not accepted. defaults is an n-tuple of default argument values corresponding to the last n positional parameters, or `None` if there are no such defaults defined. kwonlyargs is a list of keyword-only parameter names in declaration order. kwonlydefaults is a dictionary mapping parameter names from kwonlyargs to the default values used if no argument is supplied. annotations is a dictionary mapping parameter names to annotations. The special key `"return"` is used to report the function return value annotation (if any).

  Note that `signature()` and Signature Object provide the recommended API for callable introspection, and support additional behaviours (like positional-only arguments) that are sometimes encountered in extension module APIs. This function is retained primarily for use in code that needs to maintain compatibility with the Python 2 `inspect` module API.

  Changed in version 3.4: This function is now based on `signature()`, but still ignores `__wrapped__` attributes and includes the already bound first parameter in the signature output for bound methods.

  Changed in version 3.6: This method was previously documented as deprecated in favour of `signature()` in Python 3.5, but that decision has been reversed in order to restore a clearly supported standard interface for single-source Python 2/3 code migrating away from the legacy `getargspec()` API.

  Changed in version 3.7: Python only explicitly guaranteed that it preserved the declaration order of keyword-only parameters as of version 3.7, although in practice this order had always been preserved in Python 3.

inspect.getargvalues(frame)

  Get information about arguments passed into a particular frame. A named tuple `ArgInfo(args, varargs, keywords, locals)` is returned. args is a list of the argument names. varargs and keywords are the names of the `*` and `**` arguments or `None`. locals is the locals dictionary of the given frame.

  Note

  This function was inadvertently marked as deprecated in Python 3.5.

inspect.formatargvalues(args[, varargs, varkw, locals, formatarg, formatvarargs, formatvarkw, formatvalue])

  Format a pretty argument spec from the four values returned by `getargvalues()`. The format* arguments are the corresponding optional formatting functions that are called to turn names and values into strings.

  Note

  This function was inadvertently marked as deprecated in Python 3.5.

inspect.getmro(cls)

  Return a tuple of class cls’s base classes, including cls, in method resolution order. No class appears more than once in this tuple. Note that the method resolution order depends on cls’s type. Unless a very peculiar user-defined metatype is in use, cls will be the first element of the tuple.

inspect.getcallargs(func, /, *args, **kwds)

  Bind the args and kwds to the argument names of the Python function or method func, as if it was called with them. For bound methods, bind also the first argument (typically named `self`) to the associated instance. A dict is returned, mapping the argument names (including the names of the `*` and `**` arguments, if any) to their values from args and kwds. In case of invoking func incorrectly, i.e. whenever `func(*args, **kwds)` would raise an exception because of incompatible signature, an exception of the same type and the same or similar message is raised. For example:

      >>> from inspect import getcallargs
      >>> def f(a, b=1, *pos, **named):
      ...     pass
      ...
      >>> getcallargs(f, 1, 2, 3) == {'a': 1, 'named': {}, 'b': 2, 'pos': (3,)}
      True
      >>> getcallargs(f, a=2, x=4) == {'a': 2, 'named': {'x': 4}, 'b': 1, 'pos': ()}
      True
      >>> getcallargs(f)
      Traceback (most recent call last):
      ...
      TypeError: f() missing 1 required positional argument: 'a'

  Added in version 3.2.

  Deprecated since version 3.5: Use `Signature.bind()` and `Signature.bind_partial()` instead.

inspect.getclosurevars(func)

  Get the mapping of external name references in a Python function or method func to their current values. A named tuple `ClosureVars(nonlocals, globals, builtins, unbound)` is returned. nonlocals maps referenced names to lexical closure variables, globals to the function’s module globals and builtins to the builtins visible from the function body. unbound is the set of names referenced in the function that could not be resolved at all given the current module globals and builtins.

  `TypeError` is raised if func is not a Python function or method.

  Added in version 3.3.

inspect.unwrap(func, *, stop=None)

  Get the object wrapped by func. It follows the chain of `__wrapped__` attributes returning the last object in the chain.

  stop is an optional callback accepting an object in the wrapper chain as its sole argument that allows the unwrapping to be terminated early if the callback returns a true value. If the callback never returns a true value, the last object in the chain is returned as usual. For example, `signature()` uses this to stop unwrapping if any object in the chain has a `__signature__` attribute defined.

  `ValueError` is raised if a cycle is encountered.

  Added in version 3.4.

inspect.get_annotations(obj, *, globals=None, locals=None, eval_str=False, format=annotationlib.Format.VALUE)

  Compute the annotations dict for an object.

  This is an alias for `annotationlib.get_annotations()`; see the documentation of that function for more information.

  Caution

  This function may execute arbitrary code contained in annotations. See Security implications of introspecting annotations for more information.

  Added in version 3.10.

  Changed in version 3.14: This function is now an alias for `annotationlib.get_annotations()`. Calling it as `inspect.get_annotations` will continue to work.

## The interpreter stack

Some of the following functions return `FrameInfo` objects. For backwards compatibility these objects allow tuple-like operations on all attributes except `positions`. This behavior is considered deprecated and may be removed in the future.

class inspect.FrameInfo
  frame

    The frame object that the record corresponds to.

  filename

    The file name associated with the code being executed by the frame this record corresponds to.

  lineno

    The line number of the current line associated with the code being executed by the frame this record corresponds to.

  function

    The function name that is being executed by the frame this record corresponds to.

  code_context

    A list of lines of context from the source code that’s being executed by the frame this record corresponds to.

  index

    The index of the current line being executed in the `code_context` list.

  positions

    A `dis.Positions` object containing the start line number, end line number, start column offset, and end column offset associated with the instruction being executed by the frame this record corresponds to.

  Changed in version 3.5: Return a named tuple instead of a `tuple`.

  Changed in version 3.11: `FrameInfo` is now a class instance (that is backwards compatible with the previous named tuple).

class inspect.Traceback
  filename

    The file name associated with the code being executed by the frame this traceback corresponds to.

  lineno

    The line number of the current line associated with the code being executed by the frame this traceback corresponds to.

  function

    The function name that is being executed by the frame this traceback corresponds to.

  code_context

    A list of lines of context from the source code that’s being executed by the frame this traceback corresponds to.

  index

    The index of the current line being executed in the `code_context` list.

  positions

    A `dis.Positions` object containing the start line number, end line number, start column offset, and end column offset associated with the instruction being executed by the frame this traceback corresponds to.

  Changed in version 3.11: `Traceback` is now a class instance (that is backwards compatible with the previous named tuple).

Note

Keeping references to frame objects, as found in the first element of the frame records these functions return, can cause your program to create reference cycles. Once a reference cycle has been created, the lifespan of all objects which can be accessed from the objects which form the cycle can become much longer even if Python’s optional cycle detector is enabled. If such cycles must be created, it is important to ensure they are explicitly broken to avoid the delayed destruction of objects and increased memory consumption which occurs.

Though the cycle detector will catch these, destruction of the frames (and local variables) can be made deterministic by removing the cycle in a `finally` clause. This is also important if the cycle detector was disabled when Python was compiled or using `gc.disable()`. For example:

    def handle_stackframe_without_leak():
        frame = inspect.currentframe()
        try:
            # do something with the frame
        finally:
            del frame

If you want to keep the frame around (for example to print a traceback later), you can also break reference cycles by using the `frame.clear()` method.

The optional context argument supported by most of these functions specifies the number of lines of context to return, which are centered around the current line.

inspect.getframeinfo(frame, context=1)

  Get information about a frame or traceback object. A `Traceback` object is returned.

  Changed in version 3.11: A `Traceback` object is returned instead of a named tuple.

inspect.getouterframes(frame, context=1)

  Get a list of `FrameInfo` objects for a frame and all outer frames. These frames represent the calls that lead to the creation of frame. The first entry in the returned list represents frame; the last entry represents the outermost call on frame’s stack.

  Changed in version 3.5: A list of named tuples `FrameInfo(frame, filename, lineno, function, code_context, index)` is returned.

  Changed in version 3.11: A list of `FrameInfo` objects is returned.

inspect.getinnerframes(traceback, context=1)

  Get a list of `FrameInfo` objects for a traceback’s frame and all inner frames. These frames represent calls made as a consequence of frame. The first entry in the list represents traceback; the last entry represents where the exception was raised.

  Changed in version 3.5: A list of named tuples `FrameInfo(frame, filename, lineno, function, code_context, index)` is returned.

  Changed in version 3.11: A list of `FrameInfo` objects is returned.

inspect.currentframe()

  Return the frame object for the caller’s stack frame.

  CPython implementation detail: This function relies on Python stack frame support in the interpreter, which isn’t guaranteed to exist in all implementations of Python. If running in an implementation without Python stack frame support this function returns `None`.

inspect.stack(context=1)

  Return a list of `FrameInfo` objects for the caller’s stack. The first entry in the returned list represents the caller; the last entry represents the outermost call on the stack.

  Changed in version 3.5: A list of named tuples `FrameInfo(frame, filename, lineno, function, code_context, index)` is returned.

  Changed in version 3.11: A list of `FrameInfo` objects is returned.

inspect.trace(context=1)

  Return a list of `FrameInfo` objects for the stack between the current frame and the frame in which an exception currently being handled was raised in. The first entry in the list represents the caller; the last entry represents where the exception was raised.

  Changed in version 3.5: A list of named tuples `FrameInfo(frame, filename, lineno, function, code_context, index)` is returned.

  Changed in version 3.11: A list of `FrameInfo` objects is returned.

## Fetching attributes statically

Both `getattr()` and `hasattr()` can trigger code execution when fetching or checking for the existence of attributes. Descriptors, like properties, will be invoked and `__getattr__()` and `__getattribute__()` may be called.

For cases where you want passive introspection, like documentation tools, this can be inconvenient. `getattr_static()` has a similar signature as `getattr()` but avoids executing code when it fetches attributes.

inspect.getattr_static(obj, attr)
inspect.getattr_static(obj, attr, default)

  Retrieve attributes without triggering dynamic lookup via the descriptor protocol, `__getattr__()` or `__getattribute__()`.

  Note: this function may not be able to retrieve all attributes that getattr can fetch (like dynamically created attributes) and may find attributes that getattr can’t (like descriptors that raise AttributeError). It can also return descriptors objects instead of instance members.

  If the instance `__dict__` is shadowed by another member (for example a property) then this function will be unable to find instance members.

  Added in version 3.2.

`getattr_static()` does not resolve descriptors, for example slot descriptors or getset descriptors on objects implemented in C. The descriptor object is returned instead of the underlying attribute.

You can handle these with code like the following. Note that for arbitrary getset descriptors invoking these may trigger code execution:

    # example code for resolving the builtin descriptor types
    class _foo:
        __slots__ = ['foo']

    slot_descriptor = type(_foo.foo)
    getset_descriptor = type(type(open(__file__)).name)
    wrapper_descriptor = type(str.__dict__['__add__'])
    descriptor_types = (slot_descriptor, getset_descriptor, wrapper_descriptor)

    result = getattr_static(some_object, 'foo')
    if type(result) in descriptor_types:
        try:
            result = result.__get__()
        except AttributeError:
            # descriptors can raise AttributeError to
            # indicate there is no underlying value
            # in which case the descriptor itself will
            # have to do
            pass

## Current State of Generators, Coroutines, and Asynchronous Generators

When implementing coroutine schedulers and for other advanced uses of generators, it is useful to determine whether a generator is currently executing, is waiting to start or resume or execution, or has already terminated. `getgeneratorstate()` allows the current state of a generator to be determined easily.

inspect.getgeneratorstate(generator)

  Get current state of a generator-iterator.

  Possible states are:

  - GEN_CREATED: Waiting to start execution.

  - GEN_RUNNING: Currently being executed by the interpreter.

  - GEN_SUSPENDED: Currently suspended at a yield expression.

  - GEN_CLOSED: Execution has completed.

  Added in version 3.2.

inspect.getcoroutinestate(coroutine)

  Get current state of a coroutine object. The function is intended to be used with coroutine objects created by `async def` functions, but will accept any coroutine-like object that has `cr_running` and `cr_frame` attributes.

  Possible states are:

  - CORO_CREATED: Waiting to start execution.

  - CORO_RUNNING: Currently being executed by the interpreter.

  - CORO_SUSPENDED: Currently suspended at an await expression.

  - CORO_CLOSED: Execution has completed.

  Added in version 3.5.

inspect.getasyncgenstate(agen)

  Get current state of an asynchronous generator object. The function is intended to be used with asynchronous iterator objects created by `async def` functions which use the `yield` statement, but will accept any asynchronous generator-like object that has `ag_running` and `ag_frame` attributes.

  Possible states are:

  - AGEN_CREATED: Waiting to start execution.

  - AGEN_RUNNING: Currently being executed by the interpreter.

  - AGEN_SUSPENDED: Currently suspended at a yield expression.

  - AGEN_CLOSED: Execution has completed.

  Added in version 3.12.

The current internal state of the generator can also be queried. This is mostly useful for testing purposes, to ensure that internal state is being updated as expected:

inspect.getgeneratorlocals(generator)

  Get the mapping of live local variables in generator to their current values. A dictionary is returned that maps from variable names to values. This is the equivalent of calling `locals()` in the body of the generator, and all the same caveats apply.

  If generator is a generator with no currently associated frame, then an empty dictionary is returned. `TypeError` is raised if generator is not a Python generator object.

  CPython implementation detail: This function relies on the generator exposing a Python stack frame for introspection, which isn’t guaranteed to be the case in all implementations of Python. In such cases, this function will always return an empty dictionary.

  Added in version 3.3.

inspect.getcoroutinelocals(coroutine)

  This function is analogous to `getgeneratorlocals()`, but works for coroutine objects created by `async def` functions.

  Added in version 3.5.

inspect.getasyncgenlocals(agen)

  This function is analogous to `getgeneratorlocals()`, but works for asynchronous generator objects created by `async def` functions which use the `yield` statement.

  Added in version 3.12.

## Code Objects Bit Flags

Python code objects have a `co_flags` attribute, which is a bitmap of the following flags:

inspect.CO_OPTIMIZED

  The code object is optimized, using fast locals.

inspect.CO_NEWLOCALS

  If set, a new dict will be created for the frame’s `f_locals` when the code object is executed.

inspect.CO_VARARGS

  The code object has a variable positional parameter (`*args`-like).

inspect.CO_VARKEYWORDS

  The code object has a variable keyword parameter (`**kwargs`-like).

inspect.CO_NESTED

  The flag is set when the code object is a nested function.

inspect.CO_GENERATOR

  The flag is set when the code object is a generator function, i.e. a generator object is returned when the code object is executed.

inspect.CO_COROUTINE

  The flag is set when the code object is a coroutine function. When the code object is executed it returns a coroutine object. See PEP 492 for more details.

  Added in version 3.5.

inspect.CO_ITERABLE_COROUTINE

  The flag is used to transform generators into generator-based coroutines. Generator objects with this flag can be used in `await` expression, and can `yield from` coroutine objects. See PEP 492 for more details.

  Added in version 3.5.

inspect.CO_ASYNC_GENERATOR

  The flag is set when the code object is an asynchronous generator function. When the code object is executed it returns an asynchronous generator object. See PEP 525 for more details.

  Added in version 3.6.

inspect.CO_HAS_DOCSTRING

  The flag is set when there is a docstring for the code object in the source code. If set, it will be the first item in `co_consts`.

  Added in version 3.14.

inspect.CO_METHOD

  The flag is set when the code object is a function defined in class scope.

  Added in version 3.14.

Note

The flags are specific to CPython, and may not be defined in other Python implementations. Furthermore, the flags are an implementation detail, and can be removed or deprecated in future Python releases. It’s recommended to use public APIs from the `inspect` module for any introspection needs.

## Buffer flags

class inspect.BufferFlags

  This is an `enum.IntFlag` that represents the flags that can be passed to the `__buffer__()` method of objects implementing the buffer protocol.

  The meaning of the flags is explained at Buffer request types.

  SIMPLE
  WRITABLE
  FORMAT
  ND
  STRIDES
  C_CONTIGUOUS
  F_CONTIGUOUS
  ANY_CONTIGUOUS
  INDIRECT
  CONTIG
  CONTIG_RO
  STRIDED
  STRIDED_RO
  RECORDS
  RECORDS_RO
  FULL
  FULL_RO
  READ
  WRITE

  Added in version 3.12.

## Command-line interface

The `inspect` module also provides a basic introspection capability from the command line.

By default, accepts the name of a module and prints the source of that module. A class or function within the module can be printed instead by appended a colon and the qualified name of the target object.

--details

  Print information about the specified object rather than the source code