NAME

       PerlIO::via::dynamic - dynamic PerlIO layers

SYNOPSIS

        open $fh, $fname;
        $p = PerlIO::via::dynamic->new
         (translate =>
           sub { $_[1] =~ s/\$Filename[:\w\s\-\.\/\\]*\$/\$Filename: $fname\$/e},
          untranslate =>
           sub { $_[1] =~ s/\$Filename[:\w\s\-\.\/\\]*\$/\$Filename\$/});
        $p->via ($fh);
        binmode $fh, $p->via; # deprecated

DESCRIPTION

       "PerlIO::via::dynamic" is used for creating dynamic PerlIO layers. It is useful when the
       behavior or the layer depends on variables. You should not use this module as via layer
       directly (ie :via(dynamic)).

       Use the constructor to create new layers, with two arguments: translate and untranslate.
       Then use "$p-"via ($fh)> to wrap the handle.  Once <$fh> is destroyed, the temporary
       namespace for the IO layer will be removed.

       Note that PerlIO::via::dynamic uses the scalar fields to reference to the object
       representing the dynamic namespace.

OPTIONS

       translate
           A function that translate buffer upon write.

       untranslate
           A function that translate buffer upon read.

       use_read
           Use "READ" instead of "FILL" for the layer.  Useful when caller expect exact amount of
           data from read, and the "untranslate" function might return different length.

           By default "PerlIO::via::dynamic" creates line-based layer to make "translate"
           implementation easier.

AUTHORS

       Chia-liang Kao <clkao@clkao.org>

COPYRIGHT

       Copyright 2004 by Chia-liang Kao <clkao@clkao.org>.

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

       See <http://www.perl.com/perl/misc/Artistic.html>