1IO::Interactive(3)    User Contributed Perl Documentation   IO::Interactive(3)
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NAME

6       IO::Interactive - Utilities for interactive I/O
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VERSION

9       This document describes IO::Interactive version 1.02
10

SYNOPSIS

12           use IO::Interactive qw(is_interactive interactive busy);
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14           if ( is_interactive() ) {
15               print "Running interactively\n";
16           }
17
18           # or...
19
20           print {interactive} "Running interactively\n";
21
22
23           $fh = busy {
24               do_noninteractive_stuff();
25           }
26

DESCRIPTION

28       This module provides three utility subroutines that make it easier to
29       develop interactive applications.
30
31       The "ARGV" filehandle, the one that "<>" or an empty readline() uses,
32       has various magic associated with it. It's not actually opened until
33       you try to read from it. Checking "-t ARGV" before you've tried to read
34       from it might give you the wrong answer.  Not only that, you might not
35       read from "ARGV". If the value in @ARGV is the magic filename "-" (a
36       convention to mean the standard filehandle for input or output), "ARGV"
37       might actually be "STDIN".  You don't want to think about all of this.
38       This module is discussed in Perl Best Practices on page 218. Also see
39       the "ARGV" entry in perlvar and the "readline" entry in perlfunc.
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41       is_interactive()
42           This subroutine returns true if *ARGV and the currently selected
43           filehandle (usually *STDOUT) are connected to the terminal. The
44           test is considerably more sophisticated than:
45
46               -t *ARGV && -t *STDOUT
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48           as it takes into account the magic behaviour of *ARGV.
49
50           You can also pass "is_interactive" a writable filehandle, in which
51           case it requires that filehandle be connected to a terminal
52           (instead of the currently selected). The usual suspect here is
53           *STDERR:
54
55               if ( is_interactive(*STDERR) ) {
56                   carp $warning;
57               }
58
59           Note that "is_interactive" may return true in a Windows Scheduled
60           Task. See Github #6
61           (https://github.com/briandfoy/io-interactive/issues/6).
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63       interactive()
64           This subroutine returns *STDOUT if "is_interactive" is true. If
65           is_interactive() is false, "interactive" returns a filehandle that
66           does not print.
67
68           This makes it easy to create applications that print out only when
69           the application is interactive:
70
71               print {interactive} "Please enter a value: ";
72               my $value = <>;
73
74           You can also pass "interactive" a writable filehandle, in which
75           case it writes to that filehandle if it is connected to a terminal
76           (instead of writing to *STDOUT). Once again, the usual suspect is
77           *STDERR:
78
79               print {interactive(*STDERR)} $warning;
80
81       "busy {...}"
82           This subroutine takes a block as its single argument and executes
83           that block.  Whilst the block is executed, *ARGV is temporarily
84           replaced by a closed filehandle. That is, no input from *ARGV is
85           possible in a "busy" block.  Furthermore, any attempts to send
86           input into the "busy" block through *ARGV is intercepted and a
87           warning message is printed to *STDERR.  The "busy" call returns a
88           filehandle that contains the intercepted input.
89
90           A "busy" block is therefore useful to prevent attempts at input
91           when the program is busy at some non-interactive task.
92

DIAGNOSTICS

94       Unknown subroutine (%s) requested
95           This module only exports the three subroutines described above.
96           You asked for something else. Maybe you misspelled the subroutine
97           you wanted.
98

CONFIGURATION AND ENVIRONMENT

100       IO::Interactive requires no configuration files or environment
101       variables.
102

DEPENDENCIES

104       This module requires the openhandle() subroutine from the Scalar::Util
105       module.
106

INCOMPATIBILITIES

108       None reported.
109

BUGS AND LIMITATIONS

111       No bugs have been reported.
112
113       Please report any bugs or feature requests to Github
114       <https://github.com/briandfoy/io-interactive/issues>.
115

SOURCE AVAILABILITY

117       This code is in GitHub:
118
119               https://github.com/briandfoy/io-interactive
120

AUTHOR

122       Damian Conway  "<DCONWAY@cpan.org>"
123
124       Currently maintained by brian d foy "<bdfoy@cpan.org>".
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126       1.01 patch DMUEY "dmuey@cpan.org"
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129       Copyright © 2005-2021, Damian Conway "<DCONWAY@cpan.org>". All rights
130       reserved.
131
132       This module is free software; you can redistribute it and/or modify it
133       under the same terms as Perl itself.
134

DISCLAIMER OF WARRANTY

136       BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
137       FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT
138       WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER
139       PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND,
140       EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
141       WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
142       ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
143       YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
144       NECESSARY SERVICING, REPAIR, OR CORRECTION.
145
146       IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
147       WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
148       REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
149       TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
150       CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
151       SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
152       RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
153       FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
154       SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
155       DAMAGES.
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159perl v5.38.0                      2023-07-20                IO::Interactive(3)
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