29.12.inspect — Inspect live objects

Source code:Lib/inspect.py


Theinspect module provides several useful functions to help getinformation about live objects such as modules, classes, methods, functions,tracebacks, frame objects, and code objects. For example, it can help youexamine the contents of a class, retrieve the source code of a method, extractand format the argument list for a function, or get all the information you needto 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 theinterpreter stack.

29.12.1. Types and members

Thegetmembers() function retrieves the members of an object such as aclass or module. The functions whose names begin with “is” are mainlyprovided as convenient choices for the second argument togetmembers().They also help you determine when you can expect to find the following specialattributes:

TypeAttributeDescription
module__doc__documentation string
 __file__filename (missing forbuilt-in modules)
class__doc__documentation string
 __name__name with which thisclass was defined
 __qualname__qualified name
 __module__name of module in whichthis class was defined
method__doc__documentation string
 __name__name with which thismethod was defined
 __qualname__qualified name
 __func__function objectcontaining implementationof method
 __self__instance to which thismethod is bound, orNone
function__doc__documentation string
 __name__name with which thisfunction was defined
 __qualname__qualified name
 __code__code object containingcompiled functionbytecode
 __defaults__tuple of any defaultvalues for positional orkeyword parameters
 __kwdefaults__mapping of any defaultvalues for keyword-onlyparameters
 __globals__global namespace in whichthis function was defined
 __annotations__mapping of parametersnames to annotations;"return" key isreserved for returnannotations.
tracebacktb_frameframe object at thislevel
 tb_lastiindex of last attemptedinstruction in bytecode
 tb_linenocurrent line number inPython source code
 tb_nextnext inner tracebackobject (called by thislevel)
framef_backnext outer frame object(this frame’s caller)
 f_builtinsbuiltins namespace seenby this frame
 f_codecode object beingexecuted in this frame
 f_globalsglobal namespace seen bythis frame
 f_lastiindex of last attemptedinstruction in bytecode
 f_linenocurrent line number inPython source code
 f_localslocal namespace seen bythis frame
 f_restricted0 or 1 if frame is inrestricted execution mode
 f_tracetracing function for thisframe, orNone
codeco_argcountnumber of arguments (notincluding keyword onlyarguments, * or **args)
 co_codestring of raw compiledbytecode
 co_cellvarstuple of names of cellvariables (referenced bycontaining scopes)
 co_conststuple of constants usedin the bytecode
 co_filenamename of file in whichthis code object wascreated
 co_firstlinenonumber of first line inPython source code
 co_flagsbitmap ofCO_* flags,read morehere
 co_lnotabencoded mapping of linenumbers to bytecodeindices
 co_freevarstuple of names of freevariables (referenced viaa function’s closure)
 co_kwonlyargcountnumber of keyword onlyarguments (not including** arg)
 co_namename with which this codeobject was defined
 co_namestuple of names of localvariables
 co_nlocalsnumber of local variables
 co_stacksizevirtual machine stackspace required
 co_varnamestuple of names ofarguments and localvariables
generator__name__name
 __qualname__qualified name
 gi_frameframe
 gi_runningis the generator running?
 gi_codecode
 gi_yieldfromobject being iterated byyieldfrom, orNone
coroutine__name__name
 __qualname__qualified name
 cr_awaitobject being awaited on,orNone
 cr_frameframe
 cr_runningis the coroutine running?
 cr_codecode
builtin__doc__documentation string
 __name__original name of thisfunction or method
 __qualname__qualified name
 __self__instance to which amethod is bound, orNone

Changed in version 3.5:Add__qualname__ andgi_yieldfrom attributes to generators.

The__name__ attribute of generators is now set from the functionname, instead of the code name, and it can now be modified.

inspect.getmembers(object[,predicate])

Return all the members of an object in a list of (name, value) pairs sorted byname. If the optionalpredicate argument is supplied, only members for whichthe predicate returns a true value are included.

Note

getmembers() will only return class attributes defined in themetaclass when the argument is a class and those attributes have beenlisted in the metaclass’ custom__dir__().

inspect.getmoduleinfo(path)

Returns anamed tupleModuleInfo(name,suffix,mode,module_type)of values that describe how Python will interpret the file identified bypath if it is a module, orNone if it would not be identified as amodule. In that tuple,name is the name of the module without the name ofany enclosing package,suffix is the trailing part of the file name (whichmay not be a dot-delimited extension),mode is theopen() mode thatwould be used ('r' or'rb'), andmodule_type is an integer givingthe type of the module.module_type will have a value which can becompared to the constants defined in theimp module; see thedocumentation for that module for more information on module types.

Deprecated since version 3.3:You may check the file path’s suffix against the supported suffixeslisted inimportlib.machinery to infer the same information.

inspect.getmodulename(path)

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

Note that this functiononly returns a meaningful name for actualPython modules - paths that potentially refer to Python packages willstill returnNone.

Changed in version 3.3:This function is now based directly onimportlib rather than thedeprecatedgetmoduleinfo().

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 Pythoncode.

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 functionscreated by alambda 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 acoroutine function(a function defined with anasyncdef syntax).

New in version 3.5.

inspect.iscoroutine(object)

Return true if the object is acoroutine created by anasyncdef function.

New 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 regulargenerators:

defgen():yield@types.coroutinedefgen_coro():yieldassertnotisawaitable(gen())assertisawaitable(gen_coro())

New in version 3.5.

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 ifismethod(),isclass(),isfunction() orisbuiltin()are true.

This, for example, is true ofint.__add__. An object passing this testhas a__get__() method but not a__set__()method, but beyond that the set of attributes varies. A__name__ attribute is usuallysensible, and__doc__ often is.

Methods implemented via descriptors that also pass one of the other testsreturn false from theismethoddescriptor() test, simply because theother 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 both a__get__ and a__set__ method.Examples are properties (defined in Python), getsets, and members. Thelatter two are defined in C and there are more specific tests available forthose types, which is robust across Python implementations. Typically, datadescriptors will also have__name__ and__doc__ attributes(properties, getsets, and members have both of these attributes), but this isnot guaranteed.

inspect.isgetsetdescriptor(object)

Return true if the object is a getset descriptor.

CPython implementation detail: getsets are attributes defined in extension modules viaPyGetSetDef structures. For Python implementations without suchtypes, 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 viaPyMemberDef structures. For Python implementations without suchtypes, this method will always returnFalse.

29.12.2. Retrieving source code

inspect.getdoc(object)

Get the documentation string for an object, cleaned up withcleandoc().If the documentation string for an object is not provided and the object isa class, a method, a property or a descriptor, retrieve the documentationstring from the inheritance hierarchy.

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 theobject’s source code (for a class, function, or method), or at the top of thePython source file (if the object is a module). If the object’s source codeis unavailable, returnNone. This could happen if the object has beendefined 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 aTypeError 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. Thiswill fail with aTypeError if the object is a built-in module, class, orfunction.

inspect.getsourcelines(object)

Return a list of source lines and starting line number for an object. Theargument may be a module, class, method, function, traceback, frame, or codeobject. The source code is returned as a list of the lines corresponding to theobject and the line number indicates where in the original source file the firstline of code was found. AnOSError is raised if the source code cannotbe retrieved.

Changed in version 3.3:OSError is raised instead ofIOError, now an alias of theformer.

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 isreturned as a single string. AnOSError is raised if the source codecannot be retrieved.

Changed in version 3.3:OSError is raised instead ofIOError, now an alias of theformer.

inspect.cleandoc(doc)

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

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

29.12.3. Introspecting callables with the Signature object

New in version 3.3.

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

inspect.signature(callable,*,follow_wrapped=True)

Return aSignature object for the givencallable:

>>>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 tofunctools.partial() objects.

RaisesValueError if no signature can be provided, andTypeError if that type of object is not supported.

New in version 3.5:follow_wrapped parameter. PassFalse to get a signature ofcallable specifically (callable.__wrapped__ will not be used tounwrap decorated callables.)

Note

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

classinspect.Signature(parameters=None,*,return_annotation=Signature.empty)

A Signature object represents the call signature of a function and its returnannotation. For each parameter accepted by the function it stores aParameter object in itsparameters collection.

The optionalparameters argument is a sequence ofParameterobjects, which is validated to check that there are no parameters withduplicate names, and that the parameters are in the right order, i.e.positional-only first, then positional-or-keyword, and that parameters withdefaults follow parameters without defaults.

The optionalreturn_annotation argument, can be an arbitrary Python object,is the “return” annotation of the callable.

Signature objects areimmutable. UseSignature.replace() to make amodified copy.

Changed in version 3.5: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 correspondingParameter objects.

return_annotation

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

bind(*args,**kwargs)

Create a mapping from positional and keyword arguments to parameters.ReturnsBoundArguments if*args and**kwargs match thesignature, or raises aTypeError.

bind_partial(*args,**kwargs)

Works the same way asSignature.bind(), but allows the omission ofsome required arguments (mimicsfunctools.partial() behavior.)ReturnsBoundArguments, or raises aTypeError if thepassed arguments do not match the signature.

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

Create a new Signature instance based on the instance replace was invokedon. It is possible to pass differentparameters and/orreturn_annotation to override the corresponding properties of the basesignature. To remove return_annotation from the copied Signature, pass inSignature.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'"
classmethodfrom_callable(obj,*,follow_wrapped=True)

Return aSignature (or its subclass) object for a given callableobj. Passfollow_wrapped=False to get a signature ofobjwithout unwrapping its__wrapped__ chain.

This method simplifies subclassing ofSignature:

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

New in version 3.5.

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

Parameter objects areimmutable. Instead of modifying a Parameter object,you can useParameter.replace() to create a modified copy.

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

empty

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

name

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

default

The default value for the parameter. If the parameter has no defaultvalue, this attribute is set toParameter.empty.

annotation

The annotation for the parameter. If the parameter has no annotation,this attribute is set toParameter.empty.

kind

Describes how argument values are bound to the parameter. Possible values(accessible viaParameter, likeParameter.KEYWORD_ONLY):

NameMeaning
POSITIONAL_ONLY

Value must be supplied as a positionalargument.

Python has no explicit syntax for definingpositional-only parameters, but many built-inand extension module functions (especiallythose that accept only one or two parameters)accept them.

POSITIONAL_OR_KEYWORDValue may be supplied as either a keyword orpositional argument (this is the standardbinding behaviour for functions implementedin Python.)
VAR_POSITIONALA tuple of positional arguments that aren’tbound to any other parameter. Thiscorresponds to a*args parameter in aPython function definition.
KEYWORD_ONLYValue must be supplied as a keyword argument.Keyword only parameters are those whichappear after a* or*args entry in aPython function definition.
VAR_KEYWORDA dict of keyword arguments that aren’t boundto any other parameter. This corresponds to a**kwargs parameter in a Python functiondefinition.

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 invokedon. To override aParameter attribute, pass the correspondingargument. To remove a default value or/and an annotation from aParameter, passParameter.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'"

Changed in version 3.4:In Python 3.3 Parameter objects were allowed to havename settoNone if theirkind was set toPOSITIONAL_ONLY.This is no longer permitted.

classinspect.BoundArguments

Result of aSignature.bind() orSignature.bind_partial() call.Holds the mapping of arguments to the function’s parameters.

arguments

An ordered, mutable mapping (collections.OrderedDict) ofparameters’ names to arguments’ values. Contains only explicitly boundarguments. Changes inarguments will reflect inargs andkwargs.

Should be used in conjunction withSignature.parameters for anyargument processing purposes.

Note

Arguments for whichSignature.bind() orSignature.bind_partial() relied on a default value are skipped.However, if needed, useBoundArguments.apply_defaults() to addthem.

args

A tuple of positional arguments values. Dynamically computed from thearguments attribute.

kwargs

A dict of keyword arguments values. Dynamically computed from thearguments attribute.

signature

A reference to the parentSignature object.

apply_defaults()

Set default values for missing arguments.

For variable-positional arguments (*args) the default is anempty tuple.

For variable-keyword arguments (**kwargs) the default is anempty dict.

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

New in version 3.5.

Theargs andkwargs properties can be used to invokefunctions:

deftest(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.

29.12.4. Classes and functions

inspect.getclasstree(classes,unique=False)

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

inspect.getargspec(func)

Get the names and default values of a Python function’s arguments. Anamed tupleArgSpec(args,varargs,keywords,defaults) isreturned.args is a list of the argument names.varargs andkeywordsare the names of the* and** arguments orNone.defaults is atuple of default argument values orNone if there are no defaultarguments; if this tuple hasn elements, they correspond to the lastn elements listed inargs.

Deprecated since version 3.0:Usesignature() andSignature Object, which provide abetter introspecting API for callables.

inspect.getfullargspec(func)

Get the names and default values of a Python function’s arguments. Anamed tuple is returned:

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

args is a list of the argument names.varargs andvarkw are the namesof the* and** arguments orNone.defaults is ann-tupleof the default values of the lastn arguments, orNone if there are nodefault arguments.kwonlyargs is a list ofkeyword-only argument names.kwonlydefaults is a dictionary mapping namesfrom kwonlyargs to defaults.annotations is a dictionary mapping argumentnames to annotations.

The first four items in the tuple correspond togetargspec().

Changed in version 3.4:This function is now based onsignature(), but still ignores__wrapped__ attributes and includes the already bound firstparameter in the signature output for bound methods.

Deprecated since version 3.5:Usesignature() andSignature Object, which provide abetter introspecting API for callables.

inspect.getargvalues(frame)

Get information about arguments passed into a particular frame. Anamed tupleArgInfo(args,varargs,keywords,locals) isreturned.args is a list of the argument names.varargs andkeywordsare the names of the* and** arguments orNone.locals is thelocals dictionary of the given frame.

Note

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 bygetargspec() orgetfullargspec().

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 annotationand individual annotations into strings, respectively.

For example:

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

Deprecated since version 3.5:Usesignature() andSignature Object, which provide abetter introspecting API for callables.

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

Format a pretty argument spec from the four values returned bygetargvalues(). The format* arguments are the corresponding optionalformatting 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 resolutionorder. No class appears more than once in this tuple. Note that the methodresolution order depends on cls’s type. Unless a very peculiar user-definedmetatype is in use, cls will be the first element of the tuple.

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

Bind theargs andkwds to the argument names of the Python function ormethodfunc, as if it was called with them. For bound methods, bind also thefirst argument (typically namedself) to the associated instance. A dictis returned, mapping the argument names (including the names of the* and** arguments, if any) to their values fromargs andkwds. In case ofinvokingfunc incorrectly, i.e. wheneverfunc(*args,**kwds) would raisean exception because of incompatible signature, an exception of the same typeand 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'

New in version 3.2.

Deprecated since version 3.5:UseSignature.bind() andSignature.bind_partial() instead.

inspect.getclosurevars(func)

Get the mapping of external name references in a Python function ormethodfunc to their current values. Anamed tupleClosureVars(nonlocals,globals,builtins,unbound)is returned.nonlocals maps referenced names to lexical closurevariables,globals to the function’s module globals andbuiltins tothe builtins visible from the function body.unbound is the set of namesreferenced in the function that could not be resolved at all given thecurrent module globals and builtins.

TypeError is raised iffunc is not a Python function or method.

New in version 3.3.

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

Get the object wrapped byfunc. 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 chainas its sole argument that allows the unwrapping to be terminated early ifthe callback returns a true value. If the callback never returns a truevalue, the last object in the chain is returned as usual. For example,signature() uses this to stop unwrapping if any object in thechain has a__signature__ attribute defined.

ValueError is raised if a cycle is encountered.

New in version 3.4.

29.12.5. The interpreter stack

When the following functions return “frame records,” each record is anamed tupleFrameInfo(frame,filename,lineno,function,code_context,index).The tuple contains the frame object, the filename, the line number of thecurrent line,the function name, a list of lines of context from the source code, and theindex of the current line within that list.

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

Note

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

Though the cycle detector will catch these, destruction of the frames (and localvariables) can be made deterministic by removing the cycle in afinally clause. This is also important if the cycle detector wasdisabled when Python was compiled or usinggc.disable(). For example:

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

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

The optionalcontext argument supported by most of these functions specifiesthe number of lines of context to return, which are centered around the currentline.

inspect.getframeinfo(frame,context=1)

Get information about a frame or traceback object. Anamed tupleTraceback(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 framesrepresent the calls that lead to the creation offrame. The first entry in thereturned list representsframe; the last entry represents the outermost callonframe’s stack.

Changed in version 3.5:A list ofnamed tuplesFrameInfo(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. Theseframes represent calls made as a consequence offrame. The first entry in thelist representstraceback; the last entry represents where the exception wasraised.

Changed in version 3.5:A list ofnamed tuplesFrameInfo(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. Ifrunning in an implementation without Python stack frame support thisfunction returnsNone.

inspect.stack(context=1)

Return a list of frame records for the caller’s stack. The first entry in thereturned list represents the caller; the last entry represents the outermostcall on the stack.

Changed in version 3.5:A list ofnamed tuplesFrameInfo(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 theframe in which an exception currently being handled was raised in. The firstentry in the list represents the caller; the last entry represents where theexception was raised.

Changed in version 3.5:A list ofnamed tuplesFrameInfo(frame,filename,lineno,function,code_context,index)is returned.

29.12.6. Fetching attributes statically

Bothgetattr() andhasattr() can trigger code execution whenfetching or checking for the existence of attributes. Descriptors, likeproperties, will be invoked and__getattr__() and__getattribute__()may be called.

For cases where you want passive introspection, like documentation tools, thiscan be inconvenient.getattr_static() has the same signature asgetattr()but avoids executing code when it fetches attributes.

inspect.getattr_static(obj,attr,default=None)

Retrieve attributes without triggering dynamic lookup via thedescriptor protocol,__getattr__() or__getattribute__().

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

If the instance__dict__ is shadowed by another member (forexample a property) then this function will be unable to find instancemembers.

New in version 3.2.

getattr_static() does not resolve descriptors, for example slot descriptors orgetset descriptors on objects implemented in C. The descriptor objectis returned instead of the underlying attribute.

You can handle these with code like the following. Note thatfor arbitrary getset descriptors invoking these may triggercode execution:

# example code for resolving the builtin descriptor typesclass_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 dopass

29.12.7. Current State of Generators and Coroutines

When implementing coroutine schedulers and for other advanced uses ofgenerators, it is useful to determine whether a generator is currentlyexecuting, is waiting to start or resume or execution, or has alreadyterminated.getgeneratorstate() allows the current state of agenerator 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.

New in version 3.2.

inspect.getcoroutinestate(coroutine)

Get current state of a coroutine object. The function is intended to beused with coroutine objects created byasyncdef functions, butwill 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.

New in version 3.5.

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

inspect.getgeneratorlocals(generator)

Get the mapping of live local variables ingenerator to their currentvalues. A dictionary is returned that maps from variable names to values.This is the equivalent of callinglocals() in the body of thegenerator, and all the same caveats apply.

Ifgenerator is agenerator with no currently associated frame,then an empty dictionary is returned.TypeError is raised ifgenerator is not a Python generator object.

CPython implementation detail: This function relies on the generator exposing a Python stack framefor introspection, which isn’t guaranteed to be the case in allimplementations of Python. In such cases, this function will alwaysreturn an empty dictionary.

New in version 3.3.

inspect.getcoroutinelocals(coroutine)

This function is analogous togetgeneratorlocals(), butworks for coroutine objects created byasyncdef functions.

New in version 3.5.

29.12.8. Code Objects Bit Flags

Python code objects have aco_flags attribute, which is a bitmap ofthe 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’sf_locals whenthe 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_NOFREE

The flag is set if there are no free or cell variables.

inspect.CO_COROUTINE

The flag is set when the code object is a coroutine function, i.e.a coroutine object is returned when the code object is executed. SeePEP 492 for more details.

New in version 3.5.

inspect.CO_ITERABLE_COROUTINE

Used to turn generators into generator-based coroutines. Generatorobjects with this flag can be used inawait expression, and canyieldfrom coroutine objects. SeePEP 492 for more details.

New in version 3.5.

Note

The flags are specific to CPython, and may not be defined in otherPython implementations. Furthermore, the flags are an implementationdetail, and can be removed or deprecated in future Python releases.It’s recommended to use public APIs from theinspect modulefor any introspection needs.

29.12.9. Command Line Interface

Theinspect module also provides a basic introspection capabilityfrom the command line.

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

--details

Print information about the specified object rather than the source code