#!/usr/local/bin/perl
use v5.14; # strict, warnings, and say
{
  package Bad;
  sub new { bless {}, shift };
  sub broken{ "I'm broken" }
}
my $o = Bad->new;
say $o->broken;
{
    no warnings 'redefine';
    local *Bad::broken = sub { "I'm fine" };
    say $o->broken;
}
say $o->broken;