1if(3pm)                Perl Programmers Reference Guide                if(3pm)
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NAME

6       if - "use" a Perl module if a condition holds (also can "no" a module)
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SYNOPSIS

9         use if CONDITION, MODULE => ARGUMENTS;
10         no if CONDITION, MODULE => ARGUMENTS;
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DESCRIPTION

13       The "if" module is used to conditionally load or unload another module.
14       The construct
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16         use if CONDITION, MODULE => ARGUMENTS;
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18       will load MODULE only if CONDITION evaluates to true.  The above
19       statement has no effect unless "CONDITION" is true.  If the CONDITION
20       does evaluate to true, then the above line has the same effect as:
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22         use MODULE ARGUMENTS;
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24       The use of "=>" above provides necessary quoting of "MODULE".  If you
25       don't use the fat comma (eg you don't have any ARGUMENTS), then you'll
26       need to quote the MODULE.
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28   EXAMPLES
29       The following line is taken from the testsuite for File::Map:
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31         use if $^O ne 'MSWin32', POSIX => qw/setlocale LC_ALL/;
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33       If run on any operating system other than Windows, this will import the
34       functions "setlocale" and "LC_ALL" from POSIX.  On Windows it does
35       nothing.
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37       The following is used to deprecate core modules beyond a certain
38       version of Perl:
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40         use if $] > 5.016, 'deprecate';
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42       This line is taken from Text::Soundex 3.04, and marks it as deprecated
43       beyond Perl 5.16.  If you "use Text::Soundex" in Perl 5.18, for
44       example, and you have used warnings, then you'll get a warning message
45       (the deprecate module looks to see whether the calling module was
46       "use"'d from a core library directory, and if so, generates a warning),
47       unless you've installed a more recent version of Text::Soundex from
48       CPAN.
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50       You can also specify to NOT use something:
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52        no if $] ge 5.021_006, warnings => "locale";
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54       This warning category was added in the specified Perl version (a
55       development release).  Without the 'if', trying to use it in an earlier
56       release would generate an unknown warning category error.
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BUGS

59       The current implementation does not allow specification of the required
60       version of the module.
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SEE ALSO

63       Module::Requires can be used to conditionally load one or modules, with
64       constraints based on the version of the module.  Unlike "if" though,
65       Module::Requires is not a core module.
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67       Module::Load::Conditional provides a number of functions you can use to
68       query what modules are available, and then load one or more of them at
69       runtime.
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71       provide can be used to select one of several possible modules to load,
72       based on what version of Perl is running.
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AUTHOR

75       Ilya Zakharevich <mailto:ilyaz@cpan.org>.
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78       This software is copyright (c) 2002 by Ilya Zakharevich.
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80       This is free software; you can redistribute it and/or modify it under
81       the same terms as the Perl 5 programming language system itself.
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85perl v5.26.3                      2018-03-01                           if(3pm)
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