PerlIO::via::dynamic(3pm)

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 <[email protected]>

COPYRIGHT

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