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author | Jarkko Hietaniemi <jhi@iki.fi> | 1999-08-29 10:18:59 +0000 |
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committer | Jarkko Hietaniemi <jhi@iki.fi> | 1999-08-29 10:18:59 +0000 |
commit | 4438c4b75b842b6c829a7da9841e97abb875b1d8 (patch) | |
tree | 559b1a700465df1cb1ae02ada9b9c9e48dd9539f /pod/perllexwarn.pod | |
parent | 6dd159d1401b9b9973dd00c1235374efbcb27144 (diff) | |
download | perl-4438c4b75b842b6c829a7da9841e97abb875b1d8.tar.gz |
Rename warning to warnings, from Paul Marquess.
p4raw-id: //depot/cfgperl@4038
Diffstat (limited to 'pod/perllexwarn.pod')
-rw-r--r-- | pod/perllexwarn.pod | 59 |
1 files changed, 33 insertions, 26 deletions
diff --git a/pod/perllexwarn.pod b/pod/perllexwarn.pod index b946654425..8dbae0ddbc 100644 --- a/pod/perllexwarn.pod +++ b/pod/perllexwarn.pod @@ -4,7 +4,7 @@ perllexwarn - Perl Lexical Warnings =head1 DESCRIPTION -The C<use warning> pragma is a replacement for both the command line +The C<use warnings> pragma is a replacement for both the command line flag B<-w> and the equivalent Perl variable, C<$^W>. The pragma works just like the existing "strict" pragma. @@ -19,21 +19,21 @@ doesn't attempt to control the warnings will work unchanged. All warnings are enabled in a block by either of these: - use warning ; - use warning 'all' ; + use warnings ; + use warnings 'all' ; Similarly all warnings are disabled in a block by either of these: - no warning ; - no warning 'all' ; + no warnings ; + no warnings 'all' ; For example, consider the code below: - use warning ; + use warnings ; my $a ; my $b ; { - no warning ; + no warnings ; $b = 2 if $a EQ 3 ; } $b = 1 if $a NE 3 ; @@ -65,7 +65,7 @@ example, in the code below, an C<"integer overflow"> warning will only be reported for the C<$a> variable. my $a = "2:" + 3; - no warning ; + no warnings ; my $b = "2:" + 3; Note that neither the B<-w> flag or the C<$^W> can be used to @@ -143,7 +143,7 @@ details of how this flag interacts with lexical warnings. If the B<-W> flag is used on the command line, it will enable all warnings throughout the program regardless of whether warnings were disabled -locally using C<no warning> or C<$^W =0>. This includes all files that get +locally using C<no warnings> or C<$^W =0>. This includes all files that get included via C<use>, C<require> or C<do>. Think of it as the Perl equivalent of the "lint" command. @@ -197,7 +197,7 @@ or B<-X> command line flags. =back The combined effect of 3 & 4 is that it will will allow code which uses -the lexical warning pragma to control the warning behavior of $^W-type +the lexical warnings pragma to control the warning behavior of $^W-type code (using a C<local $^W=0>) if it really wants to, but not vice-versa. =head1 EXPERIMENTAL FEATURES @@ -273,30 +273,37 @@ hierarchy is: | +--- misc - -Just like the "strict" pragma any of these categories can be -combined - use warning qw(void redefine) ; - no warning qw(io syntax untie) ; +Just like the "strict" pragma any of these categories can be combined + + use warnings qw(void redefine) ; + no warnings qw(io syntax untie) ; + +Also like the "strict" pragma, if there is more than one instance of the +warnings pragma in a given scope the cumulative effect is additive. + + use warnings qw(void) ; # only "void" warnings enabled + ... + use warnings qw(io) ; # only "void" & "io" warnings enabled + ... + no warnings qw(void) ; # only "io" warnings enabled + =head2 Fatal Warnings -This feature is B<very> experimental. - The presence of the word "FATAL" in the category list will escalate any -warnings from the category specified that are detected in the lexical -scope into fatal errors. In the code below, there are 3 places where -a deprecated warning will be detected, the middle one will produce a -fatal error. - - - use warning ; +warnings from the category/categories specified that are detected in +the lexical scope into fatal errors. In the code below, there are 3 +places where a deprecated warning will be detected, the middle one will +produce a fatal error. + + + use warnings ; $a = 1 if $a EQ $b ; { - use warning qw(FATAL deprecated) ; + use warnings FATAL => qw(deprecated) ; $a = 1 if $a EQ $b ; } @@ -319,7 +326,7 @@ The experimental features need bottomed out. =head1 SEE ALSO -L<warning>. +L<warnings>. =head1 AUTHOR |