[Python-3000] PEP3102 Keyword-Only Arguments
steven.bethard at gmail.com
Mon Aug 14 19:49:36 CEST 2006
On 8/14/06, Guido van Rossum <guido at python.org> wrote:
> I believe the PEP doesn't address the opposite use case: positional
> arguments that should *not* be specified as keyword arguments. For
> example, I might want to write
> def foo(a, b): ...
> but I don't want callers to be able to call it as foo(b=1, a=2) or
> even foo(a=2, b=1).
Another use case is when you want to accept the arguments of another
callable, but you have your own positional arguments::
>>> class Wrapper(object):
... def __init__(self, func):
... self.func = func
... def __call__(self, *args, **kwargs):
... print 'calling wrapped function'
... return self.func(*args, **kwargs)
... def func(self, other):
... return self, other
>>> func(other=1, self=2)
Traceback (most recent call last):
File "<interactive input>", line 1, in ?
TypeError: __call__() got multiple values for keyword argument 'self'
It would be really nice in the example above to mark ``self`` in
``__call__`` as a positional only argument.
> Perhaps we can use ** without following identifier to signal this?
> It's not entirely analogous to * without following identifier, but at
> least somewhat similar.
I'm certainly not opposed to going this way, but I don't think it
would solve the problem above since you still need to take keyword
I'm not *in*-sane. Indeed, I am so far *out* of sane that you appear a
tiny blip on the distant coast of sanity.
--- Bucky Katt, Get Fuzzy
More information about the Python-3000