On 2015-01-29 23:25, Chris Kaynor wrote:
On Thu, Jan 29, 2015 at 2:57 PM, BartC <b...@freeuk.com> wrote:
[snip]
Putting in hints, (as as I implemented them using primitive types),
meant that functions and code no longer worked in a generic (or
polymorphic) manner. Code also changes, but the type hints aren't
maintained. I understand the Python proposal allows type hints to
be a union of expected types, but that sounds complicated.
Regarding the maintenance of type-hints, for people who heavily use
them, I would imagine they will have a static checker setup which
will regularly run and generally produce an error if the hints are
not updated. Most other people will likely only lightly use the
type-hints and may not use static checkers, and thus they probably
will get out of sync. With such a feature, my main use case would be
to aid IDEs in providing auto-complete, which I've done in the past
by adding lines like "if 0: assert isinstance(variable, type)". Most
of the functions I write do not have any such "hints" but instead
I've only generally used it in cases where the type is pretty much
fixed, but is a custom type with a more complicated API.
I suppose you could check what types the arguments are by running the
code and outputting the types supplied, and then run a script that uses
the info to modify the source, and then you can diff the result.
Here's a simple example I've come up with:
#! python3.4
# -*- coding: utf-8 -*-
import inspect
def check_hints(func):
def wrapper(*args, **kwargs):
sig = inspect.signature(func)
print('file :', inspect.getfile(func))
print('function :', func.__name__)
print('line :', inspect.getsourcelines(func)[1] + 1)
args_given = list(args)
kwargs_given = dict(kwargs)
for name in sig.parameters:
param = sig.parameters[name]
if param.kind == inspect.Parameter.POSITIONAL_OR_KEYWORD:
annotation = param.annotation
if args_given:
print('parameter : {} : {}'.format(name,
type(args_given.pop(0)).__name__))
if annotation != inspect.Parameter.empty:
print('annotation: {} : {}'.format(name,
annotation.__name__))
else:
try:
print('parameter : {} : {}'.format(name,
type(kwargs_given.pop(name)).__name__))
if annotation != inspect.Parameter.empty:
print('annotation: {} : {}'.format(name,
annotation.__name__))
except KeyError:
pass
result = func(*args, **kwargs)
print('return : {}'.format(type(result).__name__))
annotation = sig.return_annotation
if annotation != inspect.Parameter.empty:
print('annotation: {}'.format(annotation.__name__))
print()
return result
return wrapper
@check_hints
def foo(arg1: int, arg2: str, arg3: float=2.0) -> int:
pass
@check_hints
def bar(arg1, arg2, arg3=2.0):
pass
foo(1, "bar")
foo("baz", 2, 3.0)
bar(1, "bar")
bar("baz", 2, 3.0)
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