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 module attributes 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
|
|
__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;
|
|
__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_trace |
tracing function for this
frame, or |
|
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_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 |
|
generator |
__name__ |
name |
__qualname__ |
qualified name |
|
gi_frame |
frame |
|
gi_running |
is the generator running? |
|
gi_code |
code |
|
gi_yieldfrom |
object being iterated by
|
|
async generator |
__name__ |
name |
__qualname__ |
qualified name |
|
ag_await |
object being awaited on,
or |
|
ag_frame |
frame |
|
ag_running |
is the generator running? |
|
ag_code |
code |
|
coroutine |
__name__ |
name |
__qualname__ |
qualified name |
|
cr_await |
object being awaited on,
or |
|
cr_frame |
frame |
|
cr_running |
is the coroutine running? |
|
cr_code |
code |
|
cr_origin |
where coroutine was
created, or |
|
builtin |
__doc__ |
documentation string |
__name__ |
original name of this function or method |
|
__qualname__ |
qualified name |
|
__self__ |
instance to which a
method is bound, or
|
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.
- 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 thevalue
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.
- inspect.ismethod(object)¶
Return
True
if the object is a bound method written in Python.
- inspect.isfunction(object)¶
Return
True
if the object is a Python function, which includes functions created by a lambda expression.
- inspect.isgeneratorfunction(object)¶
Return
True
if the object is a Python generator function.Changed in version 3.8: Functions wrapped in
functools.partial()
now returnTrue
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 anasync def
syntax), afunctools.partial()
wrapping a coroutine function, or a sync function marked withmarkcoroutinefunction()
.Added in version 3.5.
Changed in version 3.8: Functions wrapped in
functools.partial()
now returnTrue
if the wrapped function is a coroutine function.Changed in version 3.12: Sync functions marked with
markcoroutinefunction()
now returnTrue
.
- 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 withiscoroutine()
.Added in version 3.12.
- inspect.iscoroutine(object)¶
Return
True
if the object is a coroutine created by anasync def
function.Added in version 3.5.
- inspect.isawaitable(object)¶
Return
True
if the object can be used inawait
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 returnTrue
if the wrapped function is an 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 aMethodWrapperType
.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 ifismethod()
,isclass()
,isfunction()
orisbuiltin()
are true.This, for example, is true of
int.__add__
. An object passing this test has a__get__()
method but not a__set__()
method, but 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 theismethoddescriptor()
test, simply because the other tests promise more – you can, e.g., count on having the__func__
attribute (etc) when an object passesismethod()
.
- 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 returnFalse
.
- 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 returnFalse
.
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. ReturnNone
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 aTypeError
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. ATypeError
is raised if the object is a built-in module, class, or function.
- 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. ATypeError
is raised if the object is a built-in module, class, or function.
- 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)¶
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.For objects defined in modules using stringized annotations (
from __future__ import annotations
),signature()
will attempt to automatically un-stringize the annotations usingget_annotations()
. The globals, locals, and eval_str parameters are passed intoget_annotations()
when resolving the annotations; see the documentation forget_annotations()
for instructions on how to use these parameters.Raises
ValueError
if no signature can be provided, andTypeError
if that type of object is not supported. Also, if the annotations are stringized, and eval_str is not false, theeval()
call(s) to un-stringize the annotations inget_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.
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 aParameter
object in itsparameters
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. UseSignature.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 aTypeError
.
- bind_partial(*args, **kwargs)¶
Works the same way as
Signature.bind()
, but allows the omission of some required arguments (mimicsfunctools.partial()
behavior.) ReturnsBoundArguments
, or raises aTypeError
if the passed arguments do not match the signature.
- replace(*[, parameters][, return_annotation])¶
Create a new
Signature
instance based on the instancereplace()
was invoked on. It is possible to pass different parameters and/or return_annotation to override the corresponding properties of the base signature. To removereturn_annotation
from the copiedSignature
, pass inSignature.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'"
- 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 aParameter
object, you can useParameter.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
(likeParameter.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 aParameter
attribute, pass the corresponding argument. To remove a default value or/and an annotation from aParameter
, passParameter.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'"
Changed in version 3.4: In Python 3.3
Parameter
objects were allowed to havename
set toNone
if theirkind
was set toPOSITIONAL_ONLY
. This is no longer permitted.
- class inspect.BoundArguments¶
Result of a
Signature.bind()
orSignature.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 inargs
andkwargs
.Should be used in conjunction with
Signature.parameters
for any argument processing purposes.Note
Arguments for which
Signature.bind()
orSignature.bind_partial()
relied on a default value are skipped. However, if needed, useBoundArguments.apply_defaults()
to add them.Changed in version 3.9:
arguments
is now of typedict
. Formerly, it was of typecollections.OrderedDict
.
- kwargs¶
A dict of keyword arguments values. Dynamically computed from the
arguments
attribute. Arguments that can be passed positionally are included inargs
instead.
- 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
andkwargs
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 orNone
if arbitrary positional arguments are not accepted. varkw is the name of the**
parameter orNone
if arbitrary keyword arguments are not accepted. defaults is an n-tuple of default argument values corresponding to the last n positional parameters, orNone
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 2inspect
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 legacygetargspec()
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 orNone
. 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. wheneverfunc(*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()
andSignature.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)¶
Compute the annotations dict for an object.
obj
may be a callable, class, or module. Passing in an object of any other type raisesTypeError
.Returns a dict.
get_annotations()
returns a new dict every time it’s called; calling it twice on the same object will return two different but equivalent dicts.This function handles several details for you:
If
eval_str
is true, values of typestr
will be un-stringized usingeval()
. This is intended for use with stringized annotations (from __future__ import annotations
).If
obj
doesn’t have an annotations dict, returns an empty dict. (Functions and methods always have an annotations dict; classes, modules, and other types of callables may not.)Ignores inherited annotations on classes. If a class doesn’t have its own annotations dict, returns an empty dict.
All accesses to object members and dict values are done using
getattr()
anddict.get()
for safety.Always, always, always returns a freshly created dict.
eval_str
controls whether or not values of typestr
are replaced with the result of callingeval()
on those values:If eval_str is true,
eval()
is called on values of typestr
. (Note thatget_annotations
doesn’t catch exceptions; ifeval()
raises an exception, it will unwind the stack past theget_annotations
call.)If eval_str is false (the default), values of type
str
are unchanged.
globals
andlocals
are passed in toeval()
; see the documentation foreval()
for more information. Ifglobals
orlocals
isNone
, this function may replace that value with a context-specific default, contingent ontype(obj)
:If
obj
is a module,globals
defaults toobj.__dict__
.If
obj
is a class,globals
defaults tosys.modules[obj.__module__].__dict__
andlocals
defaults to theobj
class namespace.If
obj
is a callable,globals
defaults toobj.__globals__
, although ifobj
is a wrapped function (usingfunctools.update_wrapper()
) it is first unwrapped.
Calling
get_annotations
is best practice for accessing the annotations dict of any object. See Annotations Best Practices for more information on annotations best practices.Added in version 3.10.
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 the same signature as getattr()
but avoids executing code when it fetches attributes.
- inspect.getattr_static(obj, attr, default=None)¶
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 hascr_running
andcr_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 theyield
statement, but will accept any asynchronous generator-like object that hasag_running
andag_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 byasync def
functions.Added in version 3.5.
- inspect.getasyncgenlocals(agen)¶
This function is analogous to
getgeneratorlocals()
, but works for asynchronous generator objects created byasync def
functions which use theyield
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 canyield 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.
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