package PerlIO::tee;
use strict;
require PerlIO::Util;
1;
__END__
=encoding utf-8
=head1 NAME
PerlIO::tee - Multiplex output layer
=for test_synopsis my($file, @sources, $scalar);
=head1 SYNOPSIS
open my $out, '>>:tee', $file, @sources;
$out->push_layer(tee => $file);
$out->push_layer(tee => ">> $file");
$out->push_layer(tee => \$scalar);
$out->push_layer(tee => \*FILEHANDLE);
=head1 DESCRIPTION
C<PerlIO::tee> provides a multiplex output stream like C<tee(1)>.
It makes a filehandle write to one or more files (or
scalars via the C<:scalar> layer) at the same time.
You can use C<push_layer()> (defined in C<PerlIO::Util>) to add a I<source>
to a filehandle. The I<source> may be a file name, a scalar reference, or a
filehandle. For example:
$fh->push_layer(tee => $file); # meaning "> $file"
$fh->push_layer(tee => ">>$file");# append mode
$fh->push_layer(tee => \$scalar); # via :scalar
$fh->push_layer(tee => \*OUT); # shallow copy, not duplication
You can also use C<open()> with multiple arguments.
However, it is just a syntax sugar to call C<push_layer()>: One C<:tee>
layer has a single extra output stream, so arguments C<$x, $y, $z> of C<open()>,
for example, prepares a filehandle with one default layer and two C<:tee>
layers with a internal output stream.
open my $tee, '>:tee', $x, $y, $z;
# the code above means:
# open my $tee, '>', $x;
# $tee->push_layer(tee => $y);
# $tee->push_layer(tee => $z);
$tee->get_layers(); # => "perlio", "tee($y)", "tee($z)"
$tee->pop_layer(); # "tee($z)" is popped
$tee->pop_layer(); # "tee($y)" is popped
# now $tee is a filehandle only to $x
=head1 EXAMPLE
Here is a minimal implementation of C<tee(1)>.
#!/usr/bin/perl -w
# Usage: $0 files...
use strict;
use PerlIO::Util;
*STDOUT->push_layer(tee => $_) for @ARGV;
while(read STDIN, $_, 2**12){
print;
}
__END__
=head1 SEE ALSO
L<PerlIO::Util>.
=head1 AUTHOR
Goro Fuji (藤 吾郎) E<lt>gfuji (at) cpan.orgE<gt>
=head1 LICENSE AND COPYRIGHT
Copyright (c) 2008, Goro Fuji E<lt>gfuji (at) cpan.orgE<gt>. Some rights reserved.
This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
=cut