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.\" ========================================================================
.\"
.IX Title "dynamic 3pm"
.TH dynamic 3pm "2022-11-20" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
PerlIO::via::dynamic \- dynamic PerlIO layers
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 8
\& open $fh, $fname;
\& $p = PerlIO::via::dynamic\->new
\&  (translate =>
\&    sub { $_[1] =~ s/\e$Filename[:\ew\es\e\-\e.\e/\e\e]*\e$/\e$Filename: $fname\e$/e},
\&   untranslate =>
\&    sub { $_[1] =~ s/\e$Filename[:\ew\es\e\-\e.\e/\e\e]*\e$/\e$Filename\e$/});
\& $p\->via ($fh);
\& binmode $fh, $p\->via; # deprecated
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\f(CW\*(C`PerlIO::via::dynamic\*(C'\fR is used for creating dynamic PerlIO
layers. It is useful when the behavior or the layer depends on
variables. You should not use this module as via layer directly (ie
:via(dynamic)).
.PP
Use the constructor to create new layers, with two arguments:
translate and untranslate. Then use \f(CW\*(C`$p\-\*(C'\fRvia ($fh)> to wrap the
handle.  Once <$fh> is destroyed, the temporary namespace for the \s-1IO\s0
layer will be removed.
.PP
Note that PerlIO::via::dynamic uses the scalar fields to reference to
the object representing the dynamic namespace.
.SH "OPTIONS"
.IX Header "OPTIONS"
.IP "translate" 4
.IX Item "translate"
A function that translate buffer upon \fIwrite\fR.
.IP "untranslate" 4
.IX Item "untranslate"
A function that translate buffer upon \fIread\fR.
.IP "use_read" 4
.IX Item "use_read"
Use \f(CW\*(C`READ\*(C'\fR instead of \f(CW\*(C`FILL\*(C'\fR for the layer.  Useful when caller
expect exact amount of data from read, and the \f(CW\*(C`untranslate\*(C'\fR function
might return different length.
.Sp
By default \f(CW\*(C`PerlIO::via::dynamic\*(C'\fR creates line-based layer to make
\&\f(CW\*(C`translate\*(C'\fR implementation easier.
.SH "AUTHORS"
.IX Header "AUTHORS"
Chia-liang Kao <clkao@clkao.org>
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2004 by Chia-liang Kao <clkao@clkao.org>.
.PP
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
.PP
See <http://www.perl.com/perl/misc/Artistic.html>