It's possible to define a fully qualified sub by adding the package to the name.

So I played around with sub X::foo and noticed that sub resolution happens in the surrounding package.

That looks consistent to me, it's analogue to BEGIN{ *X::foo = sub { } } where the anonymous sub carries its package context around.

Hence calling foo() will work while bar() fails, because Data::Dump wasn't imported into X::

use strict;
use warnings;
use Data::Dump qw/pp dd/;

sub X::foo { pp(\@_) }; 

BEGIN { *X::baz = sub { pp(\@_) } };


package X;

sub bar { pp(\@_) } ;

foo(1..3);                              # [1, 2, 3]
baz(1..3);                              # [1, 2, 3]

bar(4..6);                              # Undefined subroutine &X::pp 
+called

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Question: What are the use cases of that pattern?

The only thing which comes to mind is monkey patching a sub in another package without adding inner helper functions into that package.

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to Use cases for 'sub Pckg::func { }' ? by LanX

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