.. versionadded:: 3.3
+.. function:: unwrap(func, *, stop=None)
+
+ Get the object wrapped by *func*. It follows the chain of :attr:`__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,
+ :func:`signature` uses this to stop unwrapping if any object in the
+ chain has a ``__signature__`` attribute defined.
+
+ :exc:`ValueError` is raised if a cycle is encountered.
+
+ .. versionadded:: 3.4
+
+
.. _inspect-stack:
The interpreter stack
"Return tuple of base classes (including cls) in method resolution order."
return cls.__mro__
+# -------------------------------------------------------- function helpers
+
+def unwrap(func, *, stop=None):
+ """Get the object wrapped by *func*.
+
+ Follows the chain of :attr:`__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,
+ :func:`signature` uses this to stop unwrapping if any object in the
+ chain has a ``__signature__`` attribute defined.
+
+ :exc:`ValueError` is raised if a cycle is encountered.
+
+ """
+ if stop is None:
+ def _is_wrapper(f):
+ return hasattr(f, '__wrapped__')
+ else:
+ def _is_wrapper(f):
+ return hasattr(f, '__wrapped__') and not stop(f)
+ f = func # remember the original func for error reporting
+ memo = {id(f)} # Memoise by id to tolerate non-hashable objects
+ while _is_wrapper(func):
+ func = func.__wrapped__
+ id_func = id(func)
+ if id_func in memo:
+ raise ValueError('wrapper loop when unwrapping {!r}'.format(f))
+ memo.add(id_func)
+ return func
+
# -------------------------------------------------- source code extraction
def indentsize(line):
"""Return the indent size, in spaces, at the start of a line of text."""
sig = signature(obj.__func__)
return sig.replace(parameters=tuple(sig.parameters.values())[1:])
+ # Was this function wrapped by a decorator?
+ obj = unwrap(obj, stop=(lambda f: hasattr(f, "__signature__")))
+
try:
sig = obj.__signature__
except AttributeError:
if sig is not None:
return sig
- try:
- # Was this function wrapped by a decorator?
- wrapped = obj.__wrapped__
- except AttributeError:
- pass
- else:
- return signature(wrapped)
if isinstance(obj, types.FunctionType):
return Signature.from_function(obj)
import collections
import os
import shutil
+import functools
from os.path import normcase
from test.support import run_unittest, TESTFN, DirsOnSysPath
((('b', ..., ..., "positional_or_keyword"),),
...))
+ # Test we handle __signature__ partway down the wrapper stack
+ def wrapped_foo_call():
+ pass
+ wrapped_foo_call.__wrapped__ = Foo.__call__
+
+ self.assertEqual(self.signature(wrapped_foo_call),
+ ((('a', ..., ..., "positional_or_keyword"),
+ ('b', ..., ..., "positional_or_keyword")),
+ ...))
+
+
def test_signature_on_class(self):
class C:
def __init__(self, a):
self.assertEqual(self.signature(Wrapped),
((('a', ..., ..., "positional_or_keyword"),),
...))
+ # wrapper loop:
+ Wrapped.__wrapped__ = Wrapped
+ with self.assertRaisesRegex(ValueError, 'wrapper loop'):
+ self.signature(Wrapped)
def test_signature_on_lambdas(self):
self.assertEqual(self.signature((lambda a=10: a)),
self.assertNotEqual(ba, ba4)
+class TestUnwrap(unittest.TestCase):
+
+ def test_unwrap_one(self):
+ def func(a, b):
+ return a + b
+ wrapper = functools.lru_cache(maxsize=20)(func)
+ self.assertIs(inspect.unwrap(wrapper), func)
+
+ def test_unwrap_several(self):
+ def func(a, b):
+ return a + b
+ wrapper = func
+ for __ in range(10):
+ @functools.wraps(wrapper)
+ def wrapper():
+ pass
+ self.assertIsNot(wrapper.__wrapped__, func)
+ self.assertIs(inspect.unwrap(wrapper), func)
+
+ def test_stop(self):
+ def func1(a, b):
+ return a + b
+ @functools.wraps(func1)
+ def func2():
+ pass
+ @functools.wraps(func2)
+ def wrapper():
+ pass
+ func2.stop_here = 1
+ unwrapped = inspect.unwrap(wrapper,
+ stop=(lambda f: hasattr(f, "stop_here")))
+ self.assertIs(unwrapped, func2)
+
+ def test_cycle(self):
+ def func1(): pass
+ func1.__wrapped__ = func1
+ with self.assertRaisesRegex(ValueError, 'wrapper loop'):
+ inspect.unwrap(func1)
+
+ def func2(): pass
+ func2.__wrapped__ = func1
+ func1.__wrapped__ = func2
+ with self.assertRaisesRegex(ValueError, 'wrapper loop'):
+ inspect.unwrap(func1)
+ with self.assertRaisesRegex(ValueError, 'wrapper loop'):
+ inspect.unwrap(func2)
+
+ def test_unhashable(self):
+ def func(): pass
+ func.__wrapped__ = None
+ class C:
+ __hash__ = None
+ __wrapped__ = func
+ self.assertIsNone(inspect.unwrap(C()))
+
+
def test_main():
run_unittest(
TestDecorators, TestRetrievingSourceCode, TestOneliners, TestBuggyCases,
TestGetcallargsFunctions, TestGetcallargsMethods,
TestGetcallargsUnboundMethods, TestGetattrStatic, TestGetGeneratorState,
TestNoEOL, TestSignatureObject, TestSignatureBind, TestParameterObject,
- TestBoundArguments, TestGetClosureVars
+ TestBoundArguments, TestGetClosureVars, TestUnwrap
)
if __name__ == "__main__":
projects / python / commitdiff