/ 
PerlIO-Layers-0.007
River stage two • 5 direct dependents • 33 total dependents
/ PerlIO::Layers

NAME

PerlIO::Layers - Querying your filehandle's capabilities

VERSION

Version 0.007

SYNOPSIS

use PerlIO::Layers qw/query_handle/;

if (!query_handle(\*STDOUT, 'binary')) {
    ...
}

DESCRIPTION

Perl's filehandles are implemented as a stack of layers, with the bottom-most usually doing the actual IO and the higher ones doing buffering, encoding/decoding or transformations. PerlIO::Layers allows you to query the filehandle's properties concerning there layers.

SUBROUTINES

query_handle($fh, $query_name [, $layer])

This query a filehandle for some information. All queries can take an optional argument, that will test for that layer's properties instead of all layers of the handle. Currently supported queries include:

  • layer

    Check the presence of a certain layer. Unlike all other properties $layer is mandatory for this query.

  • utf8

    Check whether the filehandle/layer handles unicode

  • crlf

    Check whether the filehandle/layer does crlf translation

  • binary

    Check whether the filehandle/layer is binary. This test is pessimistic (for unknown layers it will assume it's not binary).

  • mappable

    Checks whether the filehandle/layer is memory mappable. It is the same as binary, except that the utf8 layer is accepted.

  • buffered

    Check whether the filehandle/layer is buffered.

  • readable

    Check whether the filehandle/layer is readable.

  • writeable

    Check whether the filehandle/layer is writeable.

  • open

    Check whether the filehandle/layer is open.

  • temp

    Check whether the filehandle/layer refers to a temporary file.

  • can_crlf

    Checks whether layer $argument (or any layer if $argument it not given) can do crlf translation.

get_layers($fh)

Gets information on the layers of a filehandle. It's a list with whose entries have 3 elements: the name of the layer, the arguments of the layer (may be undef) and an arrayref with the flags of the layer as strings. The flags array can contain any of these values. You probably want to use query_layers instead. query_handle provides a more high level interface to this, you should probably use that when you can.

This function is deprecated and will be removed in a future version of PerlIO::Layers.

AUTHOR

Leon Timmermans, <leont at cpan.org>

BUGS

Please report any bugs or feature requests to bug-perlio-layers at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=PerlIO-Layers. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc PerlIO::Layers

You can also look for information at:

LICENSE AND COPYRIGHT

Copyright 2010 Leon Timmermans.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.