range() is not the best way to check range?

[Paul Boddie]

John Machin wrote:
> On 19/07/2006 1:05 AM, Dan Bishop wrote:
> >
> > xrange already has __contains__.
>
> As pointed out previously, xrange is a function and one would not expect
> it to have a __contains__ method.

Well, you pointed out that range is a function, but xrange seems to be
a type...

>>> xrange
<type 'xrange'>
>>> dir(xrange)
['__class__', '__delattr__', '__doc__', '__getattribute__',
'__getitem__', '__hash__', '__init__', '__iter__', '__len__',
'__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__',
'__setattr__', '__str__']

No __contains__ method, though, at least in 2.4.1.

> The objects returned by xrange do not (according to my reading of the
> 2.4.3 version of Objects/rangeobject.c) have a __contains__ method.

As confirmed by the above evidence.

> I find it difficult to believe that an inefficient __contains__ has been
> implemented since.

So do I. As you go on to say, the usual sequence traversal mechanisms
are probably used to support the "in" operator. Whether it's a pressing
matter to add support for a more efficient mechanism depends on how
often people want to use ranges in the way described. Perhaps I'll
write a patch - who knows? ;-)

Paul