Tricking caller

• How does Hook::LexWrap make itself invisible to caller?

• Easy: It throws away the real caller and replaces it with its own version

     *CORE::GLOBAL::caller = sub {
         my ($height) = ($_[0]||0);
         my $i=1;
         my $name_cache;
         while (1) {
             my @caller = CORE::caller($i++) or return;
             $caller[3] = $name_cache if $name_cache;
             $name_cache = $caller[0] eq 'Hook::LexWrap' ? $caller[3] : '';
             next if $name_cache || $height-- != 0;
             return wantarray ? @_ ? @caller : @caller[0..2] : $caller[0];
         }
     };

• Assigning to *CORE::GLOBAL::caller replaces the built-in caller

• Calling CORE::caller invokes the built-in caller anyway

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Copyright © 2003 M. J. Dominus