Hướng dẫn python inspect stack example
Source code: Lib/inspect.py Show The 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
Changed in version 3.5: Add The Changed in version 3.7: Add Changed in version 3.10: Add inspect. getmembers (object[, predicate])¶Return all the members of an object in a list of Note
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
Note that this function only returns a meaningful name for actual Python modules - paths that potentially refer to Python packages will still return Changed in version 3.3: The
function is based directly on inspect. ismodule (object)¶Return inspect. isclass (object)¶Return inspect. ismethod (object)¶Return inspect. isfunction (object)¶Return inspect. isgeneratorfunction (object)¶Return Changed in version 3.8: Functions wrapped in
inspect. isgenerator (object)¶Return inspect. iscoroutinefunction (object)¶Return New in version 3.5. inspect. iscoroutine (object)¶Return New in version 3.5. inspect. isawaitable (object)¶Return Can also be used to distinguish generator-based coroutines from regular generators: def gen(): yield @types.coroutine def gen_coro(): yield assert not isawaitable(gen()) assert isawaitable(gen_coro()) New in version 3.5. inspect. isasyncgenfunction (object)¶Return >>> async def agen(): ... yield 1 ... >>> inspect.isasyncgenfunction(agen) True New in version 3.6. inspect. isasyncgen (object)¶Return New in version 3.6. inspect. istraceback (object)¶Return inspect. isframe (object)¶Return inspect. iscode (object)¶Return inspect. isbuiltin (object)¶Return inspect. isroutine (object)¶Return inspect. isabstract (object)¶Return inspect. ismethoddescriptor (object)¶Return This, for example, is true of Methods implemented via descriptors that also pass one of the other tests return inspect. isdatadescriptor (object)¶Return Data descriptors have a
inspect. isgetsetdescriptor (object)¶Return CPython implementation detail: getsets are attributes defined in extension modules via
inspect. ismemberdescriptor (object)¶
Return CPython implementation detail: Member descriptors are attributes defined in extension modules via Retrieving source code¶inspect. getdoc (object)¶Get the documentation string for an object, cleaned up with
Changed in version 3.5: Documentation strings are now inherited if not overridden. 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 inspect. getfile (object)¶Return the name of the (text or binary) file in which an object was defined. This will fail with a inspect. getmodule (object)¶Try to guess which module an object was defined in. Return inspect. getsourcefile (object)¶Return the name of the Python source file in which an object was defined or 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 Changed in version 3.3:
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
Changed in version 3.3: 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¶New 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 inspect. signature (callable, *, follow_wrapped=True,
globals=None, locals=None, eval_str=False)¶Return a >>> 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 Accepts a wide range of Python callables, from plain functions and classes to For objects defined in modules using stringized annotations ( Raises 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. New in
version 3.5: New in version 3.10: 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. classinspect. 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 The optional parameters argument is a sequence of
The optional return_annotation argument, can be an arbitrary Python object, is the “return” annotation of the callable. Signature objects are immutable. Use 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 corresponding 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 bind (*args, **kwargs)¶Create a mapping from positional and keyword arguments to parameters. Returns
bind_partial (*args,
**kwargs)¶Works the same way as replace (*[, parameters][, return_annotation])¶Create a new Signature instance based on the instance replace was invoked on. It is possible to pass different >>> 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, globalns=None,
localns=None)¶Return a This method simplifies subclassing of class MySignature(Signature): pass sig = MySignature.from_callable(min) assert isinstance(sig, MySignature) New in version 3.5. New in version 3.10: inspect. Parameter (name, kind, *, default=Parameter.empty, annotation=Parameter.empty)¶Parameter objects are immutable. Instead of modifying a Parameter
object, you can use Changed in version 3.5: 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 Changed in version 3.6: These parameter names are exposed by this module as names like default ¶The default value for the parameter. If the parameter has no default value, this attribute is
set to annotation ¶The annotation for the parameter. If the parameter has no annotation, this attribute is set to
kind ¶Describes how argument values are bound to the parameter. Possible values (accessible via
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 a enum value of Parameter.kind. New in version 3.8. Example: print all descriptions of arguments: >>> def foo(a, b, *, c, d=10): ... pass >>> sig = signature(foo) >>> for param in sig.parameters.values(): ... print(param.kind.description) positional or keyword positional or keyword keyword-only keyword-only replace (*[, name][, kind][, default][, annotation])¶Create a new Parameter instance based on the instance replaced was invoked on. To override a
>>> 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 have inspect. BoundArguments ¶Result of a arguments ¶A mutable mapping of parameters’ names to arguments’
values. Contains only explicitly bound arguments. Changes in Should be used in conjunction with args ¶A tuple of positional arguments values. Dynamically computed from the kwargs ¶A dict of keyword arguments values. Dynamically computed from the signature ¶A reference to the parent apply_defaults ()¶Set default values for missing arguments. For variable-positional arguments ( For variable-keyword arguments ( >>> def foo(a, b='ham', *args): pass >>> ba = inspect.signature(foo).bind('spam') >>> ba.apply_defaults() >>> ba.arguments {'a': 'spam', 'b': 'ham', 'args': ()} New in version 3.5. The
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. getargspec (func)¶Get the names and default values of a Python function’s parameters. A named tuple Deprecated since version 3.0: Use
Alternatively, use inspect. getfullargspec (func)¶Get the names and default values of a Python function’s parameters. A named tuple is returned:
args is a list of the positional parameter names. varargs is the name of the Note that Changed in version 3.4: This function is now based on Changed
in version 3.6: This method was previously documented as deprecated in favour of 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 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 by
The first seven arguments are ( The other six arguments are functions that are called to turn argument names, For example: >>> from inspect import formatargspec, getfullargspec >>> def f(a: int, b: float): ... pass ... >>> formatargspec(*getfullargspec(f)) '(a: int, b: float)' Deprecated since version 3.5: Use inspect. formatargvalues (args[,
varargs, varkw, locals, formatarg, formatvarargs, formatvarkw, formatvalue])¶Format a pretty argument spec from the four values returned by
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 >>> 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' New in version 3.2. inspect. getclosurevars (func)¶Get the mapping of external name references in a Python function or method func to their current values. A
named tuple
New in version 3.3. inspect. unwrap (func, *, stop=None)¶Get the object wrapped by func. It follows the chain of 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,
New in version 3.4. inspect. get_annotations (obj, *, globals=None, locals=None, eval_str=False)¶Compute the annotations dict for an object.
Returns a dict. This function handles several details for you:
Calling New in version 3.10. The interpreter stack¶When the following functions return “frame records,” each record is a
named tuple 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 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 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 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 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. Changed in version 3.5: A list of named tuples 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. Changed
in version 3.5: A list of named tuples 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 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. Changed in version 3.5: A list of named tuples 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. Changed in version 3.5: A list of named tuples Fetching attributes statically¶Both
For cases where you want passive introspection, like documentation tools, this can be
inconvenient. inspect. getattr_static (obj, attr,
default=None)¶Retrieve attributes without triggering dynamic lookup via the descriptor protocol, 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 New in version 3.2.
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 and Coroutines¶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. inspect. getgeneratorstate (generator)¶Get current state of a generator-iterator. Possible states are:
New 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
New in version 3.5. 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
If generator is a generator with no currently associated frame, then an empty dictionary is returned.
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. New in version 3.3. inspect. getcoroutinelocals (coroutine)¶This function is analogous to New in version 3.5. Code Objects Bit Flags¶Python code objects have a 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 inspect. CO_VARARGS ¶The
code object has a variable positional parameter ( inspect. CO_VARKEYWORDS ¶The code object has a variable keyword parameter ( 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. When the code object is executed it returns a coroutine object. See PEP 492 for more details. New 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 New 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. New 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
Command Line Interface¶The
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 |