On May 2, 8:03 am, [EMAIL PROTECTED] wrote:
> On May 1, 11:10 pm, "Gabriel Genellina" <[EMAIL PROTECTED]>
...
> > I think it's a bug, but because it should raise TypeError instead.
> > The right usage is os.path.join(*pathparts)
...
> Wow. What exactly is that * operator doing? Is it only used in
> passing args to functions? Does it just expand the list into
> individual string arguments for exactly this situation? Or does it
> have other uses?
It's used for unpacking a collection into arguments to a function.
It's also used at the other end for receiving a variable length set of
arguments. i.e.
>>> x = (1,3)
>>> def add(a, b):
return a + b
>>> add(*x)
4
>>> def add(*args):
return reduce(int.__add__, args)
>>> add(1,2,3,4,5,6)
21
>>> add(*x)
4
The same sort of thing holds for keyword arguments:
>>> def print_kw(**kw):
for k in kw:
print kw[k]
>>> print_kw(a=1, b=2)
1
2
>>> d = {'a': 1, 'b': 10, 'c': 100}
>>> print_kw(**d)
1
100
10
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