NAME
IO::Tee - Multiplex output to multiple output handles
SYNOPSIS
use IO::Tee;
$tee = IO::Tee->new($handle1, $handle2);
print $tee "foo", "bar";
my $input = <$tee>;DESCRIPTION
IO::Tee objects can be used to multiplex input and output in two different ways. The first way is to multiplex output to zero or more output handles. The IO::Tee constructor, given a list of output handles, returns a tied handle that can be written to. When written to (using print or printf), the IO::Tee object multiplexes the output to the list of handles originally passed to the constructor. As a shortcut, you can also directly pass a string or an array reference to the constructor, in which case IO::File::new is called for you with the specified argument or arguments.
The second way is to multiplex input from one input handle to zero or more output handles as it is being read. The IO::Tee constructor, given an input handle followed by a list of output handles, returns a tied handle that can be read from as well as written to. When written to, the IO::Tee object multiplexes the output to all handles passed to the constructor, as described in the previous paragraph. When read from, the IO::Tee object reads from the input handle given as the first argument to the IO::Tee constructor, then writes any data read to the output handles given as the remaining arguments to the constructor.
The IO::Tee class supports certain IO::Handle and IO::File methods related to input and output. In particular, the following methods will iterate themselves over all handles associated with the IO::Tee object, and return TRUE indicating success if and only if all associated handles returned TRUE indicating success:
- close
- truncate
- write
- syswrite
- format_write
- formline
- fcntl
- ioctl
- flush
- clearerr
- seek
The following methods perform input multiplexing as described above:
- read
- sysread
- readline
- getc
- gets
- eof
- getline
- getlines
The following methods can be used to set (but not retrieve) the current values of output-related state variables on all associated handles:
- autoflush
- output_field_separator
- output_record_separator
- format_page_number
- format_lines_per_page
- format_lines_left
- format_name
- format_top_name
- format_line_break_characters
- format_formfeed
The following methods are directly passed on to the input handle given as the first argument to the IO::Tee constructor:
- input_record_separator
- input_line_number
Note that the return value of input multiplexing methods (such as print) is always the return value of the input action, not the return value of subsequent output actions. In particular, no error is indicated by the return value if the input action itself succeeds but subsequent output multiplexing fails.
EXAMPLE
use IO::Tee;
use IO::File;
my $tee = new IO::Tee(\*STDOUT,
new IO::File(">tt1.out"), ">tt2.out");
print join(' ', $tee->handles), "\n";
$tee->output_field_separator("//");
for (1..10) { print $tee $_, "\n" }
for (1..10) { $tee->print($_, "\n") }
$tee->flush;
$tee = new IO::Tee('</etc/passwd', \*STDOUT);
my @lines = <$tee>;
print scalar(@lines);AUTHOR
Chung-chieh Shan, ken@digitas.harvard.edu
COPYRIGHT
Copyright (c) 1998 Chung-chieh Shan. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.