Function Tracing

     package Trace;
     use Filter::Simple;

     sub trace { ... }        

     FILTER_ONLY code => sub {
       s{^(\s* sub \s+ [a-zA-Z_]\w* \s* \{)}
        {$1 &Trace::trace; }xmg;
     };

• FILTER_ONLY code will not modify this:

        $z = "
        sub z {
         Oh no!
        }
        ";

• The code that's passed to the filter actually has

        $z = \034\000\000\000\001\034;

• Filter::Simple puts this back the way it was afterwards

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Copyright © 2003 M. J. Dominus