Re: foreach-loop-local var in sub

[Athanasius]

Hello warshall, and welcome to the Monastery!

Just to reinforce the explanations given by choroba and tobyink, here is what the Camel Book (4^th Edition, page 358) says about Nested subroutines:

If you are accustomed (from other programming languages) to using subroutines nested within other subroutines, each with their own private variables, you’ll have to work at it a bit in Perl. Named subroutines do not nest properly, although anonymous ones do.⁹

---

⁹ To be more precise, globally named subroutines don’t nest. Unfortunately, that’s the only kind of named subroutine declaration we have. We haven’t yet implemented lexically scoped, named subroutines (known as my subs), but when we do, they should nest correctly.

Hope that helps,

[tobyink]

FYI, Perl 5.18 will have experimental implementations of my sub, state sub and our sub. our sub is effectively the same as the existing sub keyword but can also be used to hide my sub subs, a la:

use 5.010;

our $foo = 42;

my  $foo = 99;
say $foo;  # says 99

our $foo;  # "hides" my $foo
say $foo;  # says 42

[muba]

I'm looking forward to my subs!

[LanX]

> I'm looking forward to my subs!

no need to wait it's just another syntax for my $sub =sub {}, just w/o the need to do dereferencing and occupying a scalar variable.

from Re: foreach-loop-local var in sub:

use strict;
use warnings;

foreach (0, 1) {
    my $i = $_;
    my $print = sub {
      print $i;
    };
    $print->();          # 0,1
}