Python标准库inspect检查对象

类型和成员¶

getmembers() 函数获取对象的成员，例如类或模块。函数名以"is"开始的函数主要作为 getmembers() 的第2个参数使用。它们也可用于判定某对象是否有如下的特殊属性:

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 is supplied, only members for which

the predicate returns a true value are included.

注解

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.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.

在 3.3 版更改: 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.

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 asyncdef syntax).

3.5 新版功能.

inspect.iscoroutine(object)¶

Return True if the object is a coroutine created by an

asyncdef function.

3.5 新版功能.

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:

python3 notranslate">

defgen():
yield
@types.coroutine
defgen_coro():
yield
assertnotisawaitable(gen())
assertisawaitable(gen_coro())

3.5 新版功能.

inspect.isasyncgenfunction(object)¶

Return True if the object is an asynchronous generator function,

for example:

python3 notranslate">

>>> asyncdefagen():
... yield1
...
>>> inspect.isasyncgenfunction(agen)
True

3.6 新版功能.

inspect.isasyncgen(object)¶

Return True if the object is an asynchronous generator iterator

created by an asynchronous generator function.

3.6 新版功能.

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.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, 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 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().

inspect.isdatadescriptor(object)¶

Return True if the object is a data descriptor.

Data descriptors have both a __get__ and a __set__ 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.

在 3.5 版更改: 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.

inspect.getsourcefile(object)¶

Return the name of the Python source 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.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.

在 3.3 版更改: 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.

在 3.3 版更改: 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¶

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)¶

Return a Signature object for the given callable:

>>> frominspectimportsignature
>>> deffoo(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.

Raises ValueError if no signature can be provided, and

TypeError if that type of object is not supported.

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.

3.5 新版功能: follow_wrapped parameter. Pass False to get a signature of

callable specifically (callable.__wrapped__ will not be used to

unwrap decorated callables.)

注解

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.

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,

is the "return" annotation of the callable.

Signature objects are immutable. Use Signature.replace() to make a

modified copy.

在 3.5 版更改: Signature objects are 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.

在 3.7 版更改: 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.

>>> deftest(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)¶

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

obj. Pass follow_wrapped=False to get a signature of obj

without unwrapping its __wrapped__ chain.

This method simplifies subclassing of Signature:

classMySignature(Signature):
pass
sig=MySignature.from_callable(min)
assertisinstance(sig,MySignature)

3.5 新版功能.

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() to create a modified copy.

在 3.5 版更改: Parameter objects are 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.

在 3.6 版更改: These parameter names are 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. Possible values

(accessible via Parameter, like Parameter.KEYWORD_ONLY):

名称	含义
POSITIONAL_ONLY	Value must be supplied as a positional argument. Python has no explicit syntax for defining positional-only parameters, but many built-in and extension module functions (especially those that accept only one or two parameters) accept them.
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:

>>> deffoo(a,b,*,c,d=10):
... pass
>>> sig=signature(foo)
>>> forparaminsig.parameters.values():
... if(param.kind==param.KEYWORD_ONLYand
... param.defaultisparam.empty):
... print('Parameter:',param)
Parameter: c

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.

>>> frominspectimportParameter
>>> 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'"

在 3.4 版更改: 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¶

An ordered, mutable mapping (collections.OrderedDict) 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.

注解

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.

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.

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.

>>> deffoo(a,b='ham',*args):pass
>>> ba=inspect.signature(foo).bind('spam')
>>> ba.apply_defaults()
>>> ba.arguments
OrderedDict([('a', 'spam'), ('b', 'ham'), ('args', ())])

3.5 新版功能.

The args and kwargs properties can be used to invoke

functions:

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

类与函数¶

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.getargspec(func)¶

Get the names and default values of a Python function's parameters. A

named tupleArgSpec(args,varargs,keywords,defaults) is

returned. args is a list of the parameter names. varargs and keywords

are the names of the * and ** parameters or None. defaults is a

tuple of default argument values or None if there are no default

arguments; if this tuple has n elements, they correspond to the last

n elements listed in args.

3.0 版后已移除: Use getfullargspec() for an updated API that is usually a drop-in

replacement, but also correctly handles function annotations and

keyword-only parameters.

Alternatively, use signature() and

Signature Object, which provide a

more structured introspection API for callables.

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.

在 3.4 版更改: 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.

在 3.6 版更改: 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.

在 3.7 版更改: 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 tupleArgInfo(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.

注解

This function was inadvertently marked as deprecated in Python 3.5.

inspect.formatargspec(args[, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, annotations[, formatarg, formatvarargs, formatvarkw, formatvalue, formatreturns, formatannotations]])¶

Format a pretty argument spec from the values returned by

getfullargspec().

The first seven arguments are (args, varargs, varkw,

defaults, kwonlyargs, kwonlydefaults, annotations).

The other six arguments are functions that are called to turn argument names,

* argument name, ** argument name, default values, return annotation

and individual annotations into strings, respectively.

例如:

>>> frominspectimportformatargspec,getfullargspec
>>> deff(a:int,b:float):
... pass
...
>>> formatargspec(*getfullargspec(f))
'(a: int, b: float)'

3.5 版后已移除: Use signature() and

Signature Object, which provide a

better introspecting API for callables.

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.

注解

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:

>>> frominspectimportgetcallargs
>>> deff(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'

3.2 新版功能.

3.5 版后已移除: 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 tupleClosureVars(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.

3.3 新版功能.

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.

3.4 新版功能.

The interpreter stack¶

When the following functions return "frame records," each record is a

named tuple

FrameInfo(frame,filename,lineno,function,code_context,index).

The tuple contains the frame object, the filename, the line number of the

current line,

the function name, a list of lines of context from the source code, and the

index of the current line within that list.

defhandle_stackframe_without_leak():
frame=inspect.currentframe()
try:
# do something with the frame
finally:
delframe

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 named tuple

Traceback(filename,lineno,function,code_context,index) is returned.

inspect.getouterframes(frame, context=1)¶

Get a list of frame records 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.

在 3.5 版更改: A list of named tuples

FrameInfo(frame,filename,lineno,function,code_context,index)

is returned.

inspect.getinnerframes(traceback, context=1)¶

Get a list of frame records 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.

在 3.5 版更改: A list of named tuples

FrameInfo(frame,filename,lineno,function,code_context,index)

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 frame records 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.

在 3.5 版更改: A list of named tuples

FrameInfo(frame,filename,lineno,function,code_context,index)

is returned.

inspect.trace(context=1)¶

Return a list of frame records 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.

在 3.5 版更改: A list of named tuples

FrameInfo(frame,filename,lineno,function,code_context,index)

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.

3.2 新版功能.

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')
iftype(result)indescriptor_types:
try:
result=result.__get__()
exceptAttributeError:
# descriptors can raise AttributeError to
# indicate there is no underlying value
# in which case the descriptor itself will
# have to do
pass