On 2012-06-14, at 12:17 AM, Nick Coghlan wrote:
> On Thu, Jun 14, 2012 at 1:06 PM, Yury Selivanov <yseliva...@gmail.com> wrote:
>> On 2012-06-13, at 10:52 PM, Yury Selivanov wrote:
>>> 2. signature() function support all kinds of callables:
>>> classes, metaclasses, methods, class- & staticmethods,
>>> 'functools.partials', and callable objects. If a callable
>>> object has a '__signature__' attribute it does a deepcopy
>>> of it before return.
>>
>>
>> Properly decorated functions are also supported.
>
> I'd like to see the "shared state" decorator from the previous thread
> included, as well as a short interactive interpreter session showing
> correct reporting of the signature of functools.partial instances.
OK. Below is how I want to update the PEP. Do you want to include
anything else?
Visualizing Callable Objects' Signatures
----------------------------------------
Let's define some classes and functions:
::
from inspect import signature
from functools import partial, wraps
class FooMeta(type):
def __new__(mcls, name, bases, dct, *, bar:bool=False):
return super().__new__(mcls, name, bases, dct)
def __init__(cls, name, bases, dct, **kwargs):
return super().__init__(name, bases, dct)
class Foo(metaclass=FooMeta):
def __init__(self, spam:int=42):
self.spam = spam
def __call__(self, a, b, *, c) -> tuple:
return a, b, c
def shared_vars(*shared_args):
"""Decorator factory that defines shared variables that are
passed to every invocation of the function"""
def decorator(f):
@wraps(f)
def wrapper(*args, **kwds):
full_args = shared_args + args
return f(*full_args, **kwds)
# Override signature
sig = wrapper.__signature__ = signature(f)
for __ in shared_args:
sig.parameters.popitem(last=False)
return wrapper
return decorator
@shared_vars({})
def example(_state, a, b, c):
return _state, a, b, c
def format_signature(obj):
return str(signature(obj))
Now, in the python REPL:
::
>>> format_signature(FooMeta)
'(name, bases, dct, *, bar:bool=False)'
>>> format_signature(Foo)
'(spam:int=42)'
>>> format_signature(Foo.__call__)
'(self, a, b, *, c) -> tuple'
>>> format_signature(Foo().__call__)
'(a, b, *, c) -> tuple'
>>> format_signature(partial(Foo().__call__, 1, c=3))
'(b, *, c=3) -> tuple'
>>> format_signature(partial(partial(Foo().__call__, 1, c=3), 2, c=20))
'(*, c=20) -> tuple'
>>> format_signature(example)
'(a, b, c)'
>>> format_signature(partial(example, 1, 2))
'(c)'
>>> format_signature(partial(partial(example, 1, b=2), c=3))
'(b=2, c=3)'
-
Yury
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