Don't want to do the regexp test twice

[Bengt Richter]

On 25 Jul 2003 02:17:24 GMT, bokr at oz.net (Bengt Richter) wrote:
[...]
>You can spell
>
> ...     elif setattr(obj,'mat', pat.search(line)) or obj.mat:
> ...         print repr(obj.mat), obj.mat.groups(), obj.mat.group()
>
>a little slicker if you make a special object to hold a binding to
>the pat.search result, e.g., h is the Holder instance in the following,
>which remembers the last thing passed to it and immediately returns it,
>and also returns that last thing on being called without an arg:
>
> >>> mylist
> ['', 'a', 'bc', 'def', 'ghij']
> >>> h = Holder()
> >>> for line in mylist:
> ...     if 1==2: 'naw'
> ...     elif 3==4: 'neither'
> ...     elif h(pat.search(line)):
> ...         print repr(h()), h().groups(), h().group()
> ...     elif 4==5: 'haw'
> ...     else:
> ...         print 'final else'
> ...
> final else
> final else
> final else
> <_sre.SRE_Match object at 0x007F6FC0> () def
> <_sre.SRE_Match object at 0x007F6F80> () ghi
>
>Obviously
>     ...         print repr(h()), h().groups(), h().group()
>could have been
>     ...         mat=h(); print repr(mat), mat.groups(), mat.group()
>instead.
>
Sorry, I seem to have snipped out a Holder definition, in case anyone cares:

 >>> class Holder(object):
 ...     def __call__(self, *args):
 ...         if args: self.val = args[0]
 ...         return self.val
 ...
 >>> h = Holder()
 >>> h(123)
 123
 >>> h()
 123
 >>> h(345),h(),h(678),h() # result depends on left-to-right eval here
 (345, 345, 678, 678)

Regards,
Bengt Richter