in reply to Re: Removing CODE slot in typeglob / Reversing "use subs ...;"
in thread Removing CODE slot in typeglob / Reversing "use subs ...;"

Beware of the $false in there. Your eval fails because you turned on stricture, but even with my $false; it fails, so that's good. Unfortunately it works too well.

undef $::{FOO} is the same as undef *FOO and that undefined the whole typeglob. 

our $FOO = 'foo';
undef $::{FOO};
print defined $FOO ? 'defined' : 'undef';

__END__
undef

[download]
I only want to remove the CODE slot in the typeglob.

lodin

Replies are listed 'Best First'.
Re^3: Removing CODE slot in typeglob / Reversing "use subs ...;"
by BrowserUk (Patriarch) on Jan 03, 2008 at 18:33 UTC

    Again, I'm only adressing the symptoms rather than thinking things through, but how's this? 

    #! perl -slw
use strict;
use 5.010;

our $FOO = 'fred';
sub FOO () { 'foo' }
BEGIN { undef $::{FOO}{CODE} }
say defined &FOO ? 'subroutine defined' : 'subroutine undef';
say eval 'FOO if $false; 1' ? 'FOO allowed' : 'FOO not allowed';
print $FOO;

__END__
C:\test>660264.p10
subroutine defined
FOO not allowed
fred

    [download]
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]

      It's the $false playing tricks again.

      $::{FOO} is the typeglob for FOO in main, and a typeglob can be dereferenced as a hash, and that's exactly what $::{FOO}{CODE} does. It becomes more clear if you add the arrow: $::{FOO}->{CODE}. The reason it works without the arrow is that $::{FOO} is an element of the %:: hash, so it's no different than $foo{bar}{baz}. 

      use 5.010;

our %FOO = (CODE => 'hash value');
say $::{FOO}{CODE};

__END__
hash value

      [download]

      lodin

[reply]
[d/l]
[select]
        It's the $false playing tricks again.

        Yeah. Evaling a conditional on an undefined variable in the absence of strict, is a weird way to test if something is allowed under strict.

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]

In Section Seekers of Perl Wisdom