dynamic(3) User Contributed Perl Documentation dynamic(3)

PerlIO::via::dynamic - dynamic PerlIO layers

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

"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.

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.

Chia-liang Kao <clkao@clkao.org>

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

2021-05-24 perl v5.34.0