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Postings from August 2003
On Aug 19, Randal L. Schwartz wrote:
> >>>>> "Kurt" == Kurt Starsinic <kstar@cpan.org> writes:
> Kurt> It seems very strange to me to say that an anonymous sub with
> Kurt> no private variables is "not a closure." Is not the (shorthand)
> Kurt> definition of a closure "a subroutine, associated with all its
> Kurt> bindings," even when "all" == 0?
>
> Well, we need a term for that then. I've been adovcating "closure"
> as when "all > 0", whether named or anonymous.
>
> But if you have a better term (that doesn't take more than three
> words) for the subroutines that generate a different CV when created
> as opposed to those that don't, I'm all for it.
I suggest that it's a closure when the language supports
associating bindings to the subroutine. In Perl, this is always
and only the case for anonymous subroutines, whether or not the
number of private bindings > 0.
So it seems to me that, in Perl, a named subroutine is never a
closure, and an anonymous subroutine is always a closure. The fact
that perl optimizes the special case of an anonymous subroutine with 0
private bindings is an implementation detail of interest to a tiny few.
This behavior is not guaranteed, and based on Simon's bug, I suspect
that it will change.
> If "all subroutines are closures", then the term loses its usefulness
> within the Perl world.
I'm with you 100% there, Randal.
- Kurt
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