Re: strange return value

T Beck <Tracy.Beck@xxxxxxxxxxxx> wrote in comp.lang.perl.misc:
>
> T Beck wrote:
> > fxnoria@xxxxxxxxx wrote:
> > > See these tests, the returned value is defined and has kind of a dual
> > > nature:
> > >
> > > % perl -wle 'print 2 if 0 eq ""'
> > > % perl -wle 'print 2 if 0 == ""'
> > > Argument "" isn't numeric in numeric eq (==) at -e line 1.
> > > 2
> > > % perl -wle 'sub foo { 1 for @_ } print 2 if defined foo(3)'
> > > 2
> >
>
> Argh... I completely read over the part where you pointed out it was
> defined. Apparently I haven't had enough coffee today...
>
> > I'd steer clear of relying on it unless someone can find a place in the
> > docs that says this is the way it's supposed to behave, but it
> > certainly seems to be the way that it {does} behave (for the moment,
> > anyway)
>
> It still seems to be a constant behavior, but not very comforting.
> You're right, the fact that it's returning an actual empty string is
> weird, to say the least.

Not weird at all, but normal behavior for Perl's idea of a boolean. A
boolean false has a double nature in that its numeric value is 0 and its
string value is an empty string. (A boolean true is a normal 1). Another
scalar with independent numeric and string values is $!.

So this supports the theory that what the sub returns is the boolean
result of the last comparison, arguably the "last statement executed".
More evidence:

% perl -wle 'sub foo { 1 until $_[0] } print foo("quack")'
quack

However, I'm confident in saying that this is nowhere documented. In fact
I consider this a (harmless) bug, it should behave like a plain "return;".

Anno
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