IO::Interactive(3pm) User Contributed Perl Documentation IO::Interactive(3pm)
NAME
IO::Interactive - Utilities for interactive I/O
VERSION
This document describes IO::Interactive version 1.02
SYNOPSIS
use IO::Interactive qw(is_interactive interactive busy);
if ( is_interactive() ) {
print "Running interactively\n";
}
# or...
print {interactive} "Running interactively\n";
$fh = busy {
do_noninteractive_stuff();
}
DESCRIPTION
This module provides three utility subroutines that make it easier to
develop interactive applications.
The "ARGV" filehandle, the one that "<>" or an empty "readline()" uses,
has various magic associated with it. It's not actually opened until
you try to read from it. Checking "-t ARGV" before you've tried to read
from it might give you the wrong answer. Not only that, you might not
read from "ARGV". If the value in @ARGV is the magic filename "-" (a
convention to mean the standard filehandle for input or output), "ARGV"
might actually be "STDIN". You don't want to think about all of this.
This module is discussed in Perl Best Practices on page 218. Also see
the "ARGV" entry in perlvar and the "readline" entry in perlfunc.
"is_interactive()"
This subroutine returns true if *ARGV and the currently selected
filehandle (usually *STDOUT) are connected to the terminal. The
test is considerably more sophisticated than:
-t *ARGV && -t *STDOUT
as it takes into account the magic behaviour of *ARGV.
You can also pass "is_interactive" a writable filehandle, in which
case it requires that filehandle be connected to a terminal
(instead of the currently selected). The usual suspect here is
*STDERR:
if ( is_interactive(*STDERR) ) {
carp $warning;
}
"interactive()"
This subroutine returns *STDOUT if "is_interactive" is true. If
"is_interactive()" is false, "interactive" returns a filehandle
that does not print.
This makes it easy to create applications that print out only when
the application is interactive:
print {interactive} "Please enter a value: ";
my $value = <>;
You can also pass "interactive" a writable filehandle, in which
case it writes to that filehandle if it is connected to a terminal
(instead of writing to *STDOUT). Once again, the usual suspect is
*STDERR:
print {interactive(*STDERR)} $warning;
"busy {...}"
This subroutine takes a block as its single argument and executes
that block. Whilst the block is executed, *ARGV is temporarily
replaced by a closed filehandle. That is, no input from *ARGV is
possible in a "busy" block. Furthermore, any attempts to send
input into the "busy" block through *ARGV is intercepted and a
warning message is printed to *STDERR. The "busy" call returns a
filehandle that contains the intercepted input.
A "busy" block is therefore useful to prevent attempts at input
when the program is busy at some non-interactive task.
DIAGNOSTICS
Unknown subroutine (%s) requested
This module only exports the three subroutines described above.
You asked for something else. Maybe you misspelled the subroutine
you wanted.
CONFIGURATION AND ENVIRONMENT
IO::Interactive requires no configuration files or environment
variables.
DEPENDENCIES
This module requires the "openhandle()" subroutine from the
Scalar::Util module.
INCOMPATIBILITIES
None reported.
BUGS AND LIMITATIONS
No bugs have been reported.
Please report any bugs or feature requests to Github
<https://github.com/briandfoy/io-interactive/issues>.
SOURCE AVAILABILITY
This code is in GitHub:
https://github.com/briandfoy/io-interactive
AUTHOR
Damian Conway "<DCONWAY@cpan.org>"
Currently maintained by brian d foy "<bdfoy@cpan.org>".
1.01 patch DMUEY "dmuey@cpan.org"
LICENCE AND COPYRIGHT
Copyright © 2005-2021, Damian Conway "<DCONWAY@cpan.org>". All rights
reserved.
This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
DISCLAIMER OF WARRANTY
BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT
WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER
PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND,
EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
NECESSARY SERVICING, REPAIR, OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.
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