OK, chromatic's suggestion worked fine: #!/usr/bin/perl -w
use strict;
# Undefine a subroutine safely, by name.
# From a method described by chromatic.
sub undefSub
{
no strict 'refs';
my $name = shift;
# save the glob...
local *old = *{$name};
# and restore everything else
local *new;
foreach my $type (qw(HASH IO FORMAT SCALAR ARRAY))
{
my $elem = *old{$type};
next if !defined($elem);
*new = $elem;
}
*{$name} = *new;
}
package A;
sub A { print "A::A $_[0]\n" }
package B;
@B::ISA = 'A';
$B::A = "i'm \$B::A\n\n";
package main;
A->A;
B->A; # calls A::A
print $B::A;
*{B::A} = sub { print "B::A $_[0]\n" };
A->A;
B->A; # now calls B::A
eval 'print $B::A';
undefSub('B::A');
A->A;
B->A; # now calls A::A
eval 'print $B::A'; # still intact!
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