[Python-checkins] cpython: inspect.Signature: Add 'Signature.from_callable' classmethod. Closes #17373
yury.selivanov
python-checkins at python.org
Thu Mar 27 17:12:02 CET 2014
http://hg.python.org/cpython/rev/8a4e44473fdd
changeset: 89994:8a4e44473fdd
user: Yury Selivanov <yselivanov at sprymix.com>
date: Thu Mar 27 12:09:24 2014 -0400
summary:
inspect.Signature: Add 'Signature.from_callable' classmethod. Closes #17373
files:
Doc/library/inspect.rst | 12 +++
Doc/whatsnew/3.5.rst | 4 +
Lib/inspect.py | 86 ++++++++++++++++++---------
Lib/test/test_inspect.py | 13 ++++
Misc/NEWS | 2 +
5 files changed, 87 insertions(+), 30 deletions(-)
diff --git a/Doc/library/inspect.rst b/Doc/library/inspect.rst
--- a/Doc/library/inspect.rst
+++ b/Doc/library/inspect.rst
@@ -506,6 +506,18 @@
>>> str(new_sig)
"(a, b) -> 'new return anno'"
+ .. classmethod:: Signature.from_callable(obj)
+
+ Return a :class:`Signature` (or its subclass) object for a given callable
+ ``obj``. This method simplifies subclassing of :class:`Signature`:
+
+ ::
+
+ class MySignature(Signature):
+ pass
+ sig = MySignature.from_callable(min)
+ assert isinstance(sig, MySignature)
+
.. class:: Parameter(name, kind, \*, default=Parameter.empty, annotation=Parameter.empty)
diff --git a/Doc/whatsnew/3.5.rst b/Doc/whatsnew/3.5.rst
--- a/Doc/whatsnew/3.5.rst
+++ b/Doc/whatsnew/3.5.rst
@@ -140,6 +140,10 @@
* :class:`inspect.Signature` and :class:`inspect.Parameter` are now
picklable (contributed by Yury Selivanov in :issue:`20726`).
+* New class method :meth:`inspect.Signature.from_callable`, which makes
+ subclassing of :class:`~inspect.Signature` easier (contributed
+ by Yury Selivanov and Eric Snow in :issue:`17373`).
+
Optimizations
=============
diff --git a/Lib/inspect.py b/Lib/inspect.py
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -969,7 +969,8 @@
sig = _signature_internal(func,
follow_wrapper_chains=False,
- skip_bound_arg=False)
+ skip_bound_arg=False,
+ sigcls=Signature)
except Exception as ex:
# Most of the times 'signature' will raise ValueError.
# But, it can also raise AttributeError, and, maybe something
@@ -1861,7 +1862,10 @@
return _signature_fromstr(cls, func, s, skip_bound_arg)
-def _signature_internal(obj, follow_wrapper_chains=True, skip_bound_arg=True):
+def _signature_internal(obj, *,
+ follow_wrapper_chains=True,
+ skip_bound_arg=True,
+ sigcls):
if not callable(obj):
raise TypeError('{!r} is not a callable object'.format(obj))
@@ -1869,9 +1873,12 @@
if isinstance(obj, types.MethodType):
# In this case we skip the first parameter of the underlying
# function (usually `self` or `cls`).
- sig = _signature_internal(obj.__func__,
- follow_wrapper_chains,
- skip_bound_arg)
+ sig = _signature_internal(
+ obj.__func__,
+ follow_wrapper_chains=follow_wrapper_chains,
+ skip_bound_arg=skip_bound_arg,
+ sigcls=sigcls)
+
if skip_bound_arg:
return _signature_bound_method(sig)
else:
@@ -1902,9 +1909,12 @@
# (usually `self`, or `cls`) will not be passed
# automatically (as for boundmethods)
- wrapped_sig = _signature_internal(partialmethod.func,
- follow_wrapper_chains,
- skip_bound_arg)
+ wrapped_sig = _signature_internal(
+ partialmethod.func,
+ follow_wrapper_chains=follow_wrapper_chains,
+ skip_bound_arg=skip_bound_arg,
+ sigcls=sigcls)
+
sig = _signature_get_partial(wrapped_sig, partialmethod, (None,))
first_wrapped_param = tuple(wrapped_sig.parameters.values())[0]
@@ -1915,16 +1925,18 @@
if isfunction(obj) or _signature_is_functionlike(obj):
# If it's a pure Python function, or an object that is duck type
# of a Python function (Cython functions, for instance), then:
- return Signature.from_function(obj)
+ return sigcls.from_function(obj)
if _signature_is_builtin(obj):
- return _signature_from_builtin(Signature, obj,
+ return _signature_from_builtin(sigcls, obj,
skip_bound_arg=skip_bound_arg)
if isinstance(obj, functools.partial):
- wrapped_sig = _signature_internal(obj.func,
- follow_wrapper_chains,
- skip_bound_arg)
+ wrapped_sig = _signature_internal(
+ obj.func,
+ follow_wrapper_chains=follow_wrapper_chains,
+ skip_bound_arg=skip_bound_arg,
+ sigcls=sigcls)
return _signature_get_partial(wrapped_sig, obj)
sig = None
@@ -1935,23 +1947,29 @@
# in its metaclass
call = _signature_get_user_defined_method(type(obj), '__call__')
if call is not None:
- sig = _signature_internal(call,
- follow_wrapper_chains,
- skip_bound_arg)
+ sig = _signature_internal(
+ call,
+ follow_wrapper_chains=follow_wrapper_chains,
+ skip_bound_arg=skip_bound_arg,
+ sigcls=sigcls)
else:
# Now we check if the 'obj' class has a '__new__' method
new = _signature_get_user_defined_method(obj, '__new__')
if new is not None:
- sig = _signature_internal(new,
- follow_wrapper_chains,
- skip_bound_arg)
+ sig = _signature_internal(
+ new,
+ follow_wrapper_chains=follow_wrapper_chains,
+ skip_bound_arg=skip_bound_arg,
+ sigcls=sigcls)
else:
# Finally, we should have at least __init__ implemented
init = _signature_get_user_defined_method(obj, '__init__')
if init is not None:
- sig = _signature_internal(init,
- follow_wrapper_chains,
- skip_bound_arg)
+ sig = _signature_internal(
+ init,
+ follow_wrapper_chains=follow_wrapper_chains,
+ skip_bound_arg=skip_bound_arg,
+ sigcls=sigcls)
if sig is None:
# At this point we know, that `obj` is a class, with no user-
@@ -1973,7 +1991,7 @@
if text_sig:
# If 'obj' class has a __text_signature__ attribute:
# return a signature based on it
- return _signature_fromstr(Signature, obj, text_sig)
+ return _signature_fromstr(sigcls, obj, text_sig)
# No '__text_signature__' was found for the 'obj' class.
# Last option is to check if its '__init__' is
@@ -1993,9 +2011,11 @@
call = _signature_get_user_defined_method(type(obj), '__call__')
if call is not None:
try:
- sig = _signature_internal(call,
- follow_wrapper_chains,
- skip_bound_arg)
+ sig = _signature_internal(
+ call,
+ follow_wrapper_chains=follow_wrapper_chains,
+ skip_bound_arg=skip_bound_arg,
+ sigcls=sigcls)
except ValueError as ex:
msg = 'no signature found for {!r}'.format(obj)
raise ValueError(msg) from ex
@@ -2015,10 +2035,6 @@
raise ValueError('callable {!r} is not supported by signature'.format(obj))
-def signature(obj):
- '''Get a signature object for the passed callable.'''
- return _signature_internal(obj)
-
class _void:
'''A private marker - used in Parameter & Signature'''
@@ -2464,6 +2480,10 @@
def from_builtin(cls, func):
return _signature_from_builtin(cls, func)
+ @classmethod
+ def from_callable(cls, obj):
+ return _signature_internal(obj, sigcls=cls)
+
@property
def parameters(self):
return self._parameters
@@ -2723,6 +2743,12 @@
return rendered
+
+def signature(obj):
+ '''Get a signature object for the passed callable.'''
+ return Signature.from_callable(obj)
+
+
def _main():
""" Logic for inspecting an object given at command line """
import argparse
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -2517,6 +2517,19 @@
self.assertEqual(self.signature(Spam.foo),
self.signature(Ham.foo))
+ def test_signature_from_callable_python_obj(self):
+ class MySignature(inspect.Signature): pass
+ def foo(a, *, b:1): pass
+ foo_sig = MySignature.from_callable(foo)
+ self.assertTrue(isinstance(foo_sig, MySignature))
+
+ @unittest.skipIf(MISSING_C_DOCSTRINGS,
+ "Signature information for builtins requires docstrings")
+ def test_signature_from_callable_builtin_obj(self):
+ class MySignature(inspect.Signature): pass
+ sig = MySignature.from_callable(_pickle.Pickler)
+ self.assertTrue(isinstance(sig, MySignature))
+
class TestParameterObject(unittest.TestCase):
def test_signature_parameter_kinds(self):
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -109,6 +109,8 @@
- Issue #20726: inspect.signature: Make Signature and Parameter picklable.
+- Issue #17373: Add inspect.Signature.from_callable method.
+
Documentation
-------------
--
Repository URL: http://hg.python.org/cpython
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