Karthikeyan Singaravelan <tir.kar...@gmail.com> added the comment:
Adding my analysis here which is also at related issue : issue30129. On the
attached program written by @skip.montanaro both c.sum and Child.sum return
None for inspect.getdocs thus docstrings in pydoc are empty which can be fixed
in both functools and inspect module as below :
1. When we do inspect.getdoc(c.sum) where c is a partialmethod it looks for
obj.__doc__ (c.sum.__doc__) returning partialmethod.__doc__ ("new function with
partial...") instead of checking if c.sum is a partial method and returning
obj.func.__doc__ which contains the relevant doc ("sum doc"). Thus getdoc needs
to check before trying for obj.__doc__ if the obj is a partialmethod or partial
object thus returning the original function object.
2. When we do inspect.getdoc(Child.sum) it looks for obj.__doc__
(Child.sum.__doc__) and since Child.sum is a partialmethod which has __get__
overridden it calls _make_unbound_method that returns a _method object with no
doc and thus returning None. partialmethod object copies objects from the given
function at [0] and the actual object is returned at [1] . Here self.func has
the original function in this case Base.sum and _method._partialmethod has
reference to Base.sum which contains the relevant docs but _method itself has
no docs thus pydoc doesn't get any docs. So we can set _method.__doc__ =
self.func.__doc__ and getdoc can pick up the docs.
[0]
https://github.com/python/cpython/blob/f1b9ad3d38c11676b45edcbf2369239bae436e56/Lib/functools.py#L368
[1]
https://github.com/python/cpython/blob/f1b9ad3d38c11676b45edcbf2369239bae436e56/Lib/functools.py#L401
Before patch partialmethod.__doc__ :
$ ./python.exe
>>> import functools, inspect
>>> inspect.getdoc(functools.partial(int, base=2))
'partial(func, *args, **keywords) - new function with partial application\nof
the given arguments and keywords.'
After patch returns int.__doc__ :
./python.exe
>>> import functools, inspect
>>> inspect.getdoc(functools.partial(int, base=2))
"int([x]) -> integer\nint(x, base=10) -> integer\n\nConvert a number or string
to an integer ..." # Trimmed
# Patch
diff --git a/Lib/functools.py b/Lib/functools.py
index ab7d71e126..751f67fcd0 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -398,6 +398,7 @@ class partialmethod(object):
return self.func(*call_args, **call_keywords)
_method.__isabstractmethod__ = self.__isabstractmethod__
_method._partialmethod = self
+ _method.__doc__ = self.func.__doc__ or self.__doc__
return _method
def __get__(self, obj, cls):
diff --git a/Lib/inspect.py b/Lib/inspect.py
index b8a142232b..2c796546b2 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -600,6 +600,9 @@ def getdoc(object):
All tabs are expanded to spaces. To clean up docstrings that are
indented to line up with blocks of code, any whitespace than can be
uniformly removed from the second line onwards is removed."""
+ if isinstance(object, (functools.partialmethod, functools.partial)):
+ return object.func.__doc__
+
try:
doc = object.__doc__
except AttributeError:
----------
nosy: +xtreak
Added file: https://bugs.python.org/file47910/bpo30129.py
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<https://bugs.python.org/issue12154>
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