Garrett Goebel wrote:
>
> Let's see if I've got this straight. To paraphrase Damian's
> RFC 77 for reduce:
>
> If a C<grep>'s block were terminated by a call to C<last>,
> grep immediately returns the last block value (i.e. C<undef>
> on the first block call, $_[0] otherwise). Or maybe that's @_
> otherwise...
No; I think you have it right down here:
> The end result would be that if C<last> occured the first time that
> grep's block was evaluated, an empty list would be returned.
> I don't know how grep works internally. I don't know if grep pushes
> elements into @a one at a time, or if it returns a finished list of
> elements which pass the conditional block. If it is the latter as I
> assume, a short-circuited grep would return a list of all the
> elements of @b that had passed through to that point.
Actually, that's what it would do regardless of the internal
implementation. Either way, the result (assigned to @a) is the
list of items which passed the condition, up to the point the
loop was terminated via "last".
> > So: should
> >
> > scalar grep { 1 and last } LIST
> >
> > return 1, if LIST is not empty,
Yes. The first item in LIST passed the condition,
and then the loop terminated.
> > scalar grep { 0 or last } LIST
> >
> > return 0?
Yep.
These are scalar contexts; we're asking for the number of
items in the result.
--
John Porter
We're building the house of the future together.
