Filter::Util::Call

• The filter on the previous slide does not honor no Rot13

• And how could it?

  • The filter itself gets the no Rot13 before the compiler does!

• However, it's easy to make it honor ab Ebg13; directives:

           sub unimport {
            warn "Unimport...\n";
            filter_del();
           }

• Now the filter gets the ab Ebg13; line

  • Rot13s it to no Rot13;

  • Returns it to the compiler

  • The compiler compiles the line and calls Rot13::unimport

  • unimport deletes the filter

  • The parsing and compilation process continues as usual

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Copyright © 2003 M. J. Dominus