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

6       warnings - Perl pragma to control optional warnings
7

SYNOPSIS

9           use warnings;
10           no warnings;
11
12           use warnings "all";
13           no warnings "all";
14
15           use warnings::register;
16           if (warnings::enabled()) {
17               warnings::warn("some warning");
18           }
19
20           if (warnings::enabled("void")) {
21               warnings::warn("void", "some warning");
22           }
23
24           if (warnings::enabled($object)) {
25               warnings::warn($object, "some warning");
26           }
27
28           warnings::warnif("some warning");
29           warnings::warnif("void", "some warning");
30           warnings::warnif($object, "some warning");
31

DESCRIPTION

33       The "warnings" pragma is a replacement for the command line flag "-w",
34       but the pragma is limited to the enclosing block, while the flag is
35       global.  See perllexwarn for more information.
36
37       If no import list is supplied, all possible warnings are either enabled
38       or disabled.
39
40       A number of functions are provided to assist module authors.
41
42       use warnings::register
43           Creates a new warnings category with the same name as the package
44           where the call to the pragma is used.
45
46       warnings::enabled()
47           Use the warnings category with the same name as the current pack‐
48           age.
49
50           Return TRUE if that warnings category is enabled in the calling
51           module.  Otherwise returns FALSE.
52
53       warnings::enabled($category)
54           Return TRUE if the warnings category, $category, is enabled in the
55           calling module.  Otherwise returns FALSE.
56
57       warnings::enabled($object)
58           Use the name of the class for the object reference, $object, as the
59           warnings category.
60
61           Return TRUE if that warnings category is enabled in the first scope
62           where the object is used.  Otherwise returns FALSE.
63
64       warnings::warn($message)
65           Print $message to STDERR.
66
67           Use the warnings category with the same name as the current pack‐
68           age.
69
70           If that warnings category has been set to "FATAL" in the calling
71           module then die. Otherwise return.
72
73       warnings::warn($category, $message)
74           Print $message to STDERR.
75
76           If the warnings category, $category, has been set to "FATAL" in the
77           calling module then die. Otherwise return.
78
79       warnings::warn($object, $message)
80           Print $message to STDERR.
81
82           Use the name of the class for the object reference, $object, as the
83           warnings category.
84
85           If that warnings category has been set to "FATAL" in the scope
86           where $object is first used then die. Otherwise return.
87
88       warnings::warnif($message)
89           Equivalent to:
90
91               if (warnings::enabled())
92                 { warnings::warn($message) }
93
94       warnings::warnif($category, $message)
95           Equivalent to:
96
97               if (warnings::enabled($category))
98                 { warnings::warn($category, $message) }
99
100       warnings::warnif($object, $message)
101           Equivalent to:
102
103               if (warnings::enabled($object))
104                 { warnings::warn($object, $message) }
105
106       See "Pragmatic Modules" in perlmodlib and perllexwarn.
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110perl v5.8.8                       2001-09-21                     warnings(3pm)
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