>
> It’s obvious but there is one easy way to shorten the code: using
> **kwargs. It’s way shorter but the down sides are:
- the “real” function signature gets hidden so IDEs for example won’t pick
> it up
> - the error when you make a mistake when calling is not in your code
> anymore but one level down.
This is confusing. One could imagine solving this specific case by having a
> type annotation of “this function has the types of that function”. Maybe:
> def _open(*args: args_of_(sync_open), **kwargs: kwargs_of(sync_open) ->
> return_of(sync_open): But of course this only solves the case where there
> is a 1:1 mapping. / Anders
These problems could be solved by a decorator that accepts string
representation of the signature. The decorator would then have to parse the
signature at importing time and set it to the __signature__ attribute on
the resultant function. This decorator would also need to bind the
arguments e.g. sig.bind(*args, **kwargs), to handle out of order positional
arguments. Therefore this would raise an error in the decorator,
essentially solving your second point.
This would make the example look like this, a lot clearer in my opionion:
@signature('''(file, mode='r', buffering=-1, encoding=None, errors=None,
newline=None,
closefd=True, opener=None, *, loop=None,
executor=None)''')
def open(*args, **kwargs):
return AiofilesContextManager(_open(*args, **kwargs))
@asyncio.coroutine
def _open(*args, loop=None, executor=None, **kwargs):
"""Open an asyncio file."""
if loop is None:
loop = asyncio.get_event_loop()
cb = partial(sync_open, *args, **kwargs)
f = yield from loop.run_in_executor(executor, cb)
return wrap(f, loop=loop, executor=executor)
Ben Lewis
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