What's a Filter?

• A filter gets the Perl source code before the parser does

• It can transform the code any way it wants to

• Then it hands the result to Perl

• For example:

  • The source code file might be compressed

    • A filter can uncompress it before Perl sees it

  • The source code file might be encrypted

    • A filter can decrypt it before Perl sees it

  • The source code file might contain non-Perl features like macros

    • A filter can translate these to Perl before Perl sees it

• Filtering is described in the beautifully-written perlfilter man page

  • Much of this work was done by Paul Marquess

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Copyright © 2003 M. J. Dominus