X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperllexwarn.pod;h=f250fb41ef5749c5e9e9225b57d1dd8be1a187aa;hb=3f7c398ef4badd9c6ec5b40ea29141484c160f63;hp=0052d33ff2bc44e2d25461e6eef4cf8f9fb3347e;hpb=ee8c7f5465f003860e2347a2946abacac39bd9b9;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perllexwarn.pod b/pod/perllexwarn.pod index 0052d33..f250fb4 100644 --- a/pod/perllexwarn.pod +++ b/pod/perllexwarn.pod @@ -30,18 +30,17 @@ Similarly all warnings are disabled in a block by either of these: For example, consider the code below: use warnings ; - my $a ; - my $b ; + my @a ; { no warnings ; - $b = 2 if $a EQ 3 ; + my $b = @a[0] ; } - $b = 1 if $a NE 3 ; + my $c = @a[0]; The code in the enclosing block has warnings enabled, but the inner -block has them disabled. In this case that means that the use of the C -operator won't trip a C<"Use of EQ is deprecated"> warning, but the use of -C will produce a C<"Use of NE is deprecated"> warning. +block has them disabled. In this case that means the assignment to the +scalar C<$c> will trip the C<"Scalar value @a[0] better written as $a[0]"> +warning, but the assignment to the scalar C<$b> will not. =head2 Default Warnings and Optional Warnings @@ -100,7 +99,7 @@ disable compile-time warnings you need to rewrite the code like this: my $b ; chop $b ; } -The other big problem with C<$^W> is that way you can inadvertently +The other big problem with C<$^W> is the way you can inadvertently change the warning setting in unexpected places in your code. For example, when the code below is run (without the B<-w> flag), the second call to C will trip a C<"Use of uninitialized value"> warning, whereas @@ -208,10 +207,12 @@ The current hierarchy is: all -+ | - +- chmod + +- assertions | +- closure | + +- deprecated + | +- exiting | +- glob @@ -222,6 +223,8 @@ The current hierarchy is: | | | +- exec | | + | +- layer + | | | +- newline | | | +- pipe @@ -266,8 +269,6 @@ The current hierarchy is: | | | +- bareword | | - | +- deprecated - | | | +- digit | | | +- parenthesis @@ -286,7 +287,7 @@ The current hierarchy is: | +- taint | - +- umask + +- threads | +- uninitialized | @@ -297,8 +298,6 @@ The current hierarchy is: +- utf8 | +- void - | - +- y2k Just like the "strict" pragma any of these categories can be combined @@ -317,31 +316,60 @@ C pragma in a given scope the cumulative effect is additive. To determine which category a specific warning has been assigned to see L. +Note: In Perl 5.6.1, the lexical warnings category "deprecated" was a +sub-category of the "syntax" category. It is now a top-level category +in its own right. + + =head2 Fatal Warnings The presence of the word "FATAL" in the category list will escalate any warnings detected from the categories specified 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. - +into fatal errors. In the code below, the use of C