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 and the list of built-in
36       warning categories.
37
38       If no import list is supplied, all possible warnings are either enabled
39       or disabled.
40
41       A number of functions are provided to assist module authors.
42
43       use warnings::register
44           Creates a new warnings category with the same name as the package
45           where the call to the pragma is used.
46
47       warnings::enabled()
48           Use the warnings category with the same name as the current
49           package.
50
51           Return TRUE if that warnings category is enabled in the calling
52           module.  Otherwise returns FALSE.
53
54       warnings::enabled($category)
55           Return TRUE if the warnings category, $category, is enabled in the
56           calling module.  Otherwise returns FALSE.
57
58       warnings::enabled($object)
59           Use the name of the class for the object reference, $object, as the
60           warnings category.
61
62           Return TRUE if that warnings category is enabled in the first scope
63           where the object is used.  Otherwise returns FALSE.
64
65       warnings::fatal_enabled()
66           Return TRUE if the warnings category with the same name as the
67           current package has been set to FATAL in the calling module.
68           Otherwise returns FALSE.
69
70       warnings::fatal_enabled($category)
71           Return TRUE if the warnings category $category has been set to
72           FATAL in the calling module.  Otherwise returns FALSE.
73
74       warnings::fatal_enabled($object)
75           Use the name of the class for the object reference, $object, as the
76           warnings category.
77
78           Return TRUE if that warnings category has been set to FATAL in the
79           first scope where the object is used.  Otherwise returns FALSE.
80
81       warnings::warn($message)
82           Print $message to STDERR.
83
84           Use the warnings category with the same name as the current
85           package.
86
87           If that warnings category has been set to "FATAL" in the calling
88           module then die. Otherwise return.
89
90       warnings::warn($category, $message)
91           Print $message to STDERR.
92
93           If the warnings category, $category, has been set to "FATAL" in the
94           calling module then die. Otherwise return.
95
96       warnings::warn($object, $message)
97           Print $message to STDERR.
98
99           Use the name of the class for the object reference, $object, as the
100           warnings category.
101
102           If that warnings category has been set to "FATAL" in the scope
103           where $object is first used then die. Otherwise return.
104
105       warnings::warnif($message)
106           Equivalent to:
107
108               if (warnings::enabled())
109                 { warnings::warn($message) }
110
111       warnings::warnif($category, $message)
112           Equivalent to:
113
114               if (warnings::enabled($category))
115                 { warnings::warn($category, $message) }
116
117       warnings::warnif($object, $message)
118           Equivalent to:
119
120               if (warnings::enabled($object))
121                 { warnings::warn($object, $message) }
122
123       warnings::register_categories(@names)
124           This registers warning categories for the given names and is
125           primarily for use by the warnings::register pragma, for which see
126           perllexwarn.
127
128       See "Pragmatic Modules" in perlmodlib and perllexwarn.
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132perl v5.16.3                      2013-03-04                     warnings(3pm)