While investigating common::sense, I noticed the exhortation to use FATAL warnings. I don't remember seeing this option before, so I thought I'd try it out: 

$ perl -le 'use warnings qw(FATAL); my $a = "2:" + 3; print $a'
5

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Hmmm. That didn't work so well. Did I do something wrong? 
$ perl -le 'use warnings; my $a = "2:" + 3; print $a'
Argument "2:" isn't numeric in addition (+) at -e line 1.
5

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Nope, the warning message comes up fine here... well, maybe the "all" is only implied when there actually are no arguments at all. 
$ perl -le 'use warnings qw(FATAL all); my $a = "2:" + 3; print $a'
Argument "2:" isn't numeric in addition (+) at -e line 1.

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Aha. There we go. FATAL only works when giving another option. I have to admit, that was unexpected. At the very least, if FATAL with no more arguments doesn't imply "all", I would hope for a warning of some sort. It is the warnings pragma, after all! :-)

(*) I was looking at common::sense as a point of comparison. I'm not in agreement with all of the authors' conclusions, but the concepts are good: automatically engaging strict, warnings, oft-used features, etc., with a single use call rather than mandating a whole bunch of boilerplate. I'd be tempted to use such a module to import a bunch of other stuff, too, but will probably hold off on that as it would start to hide where our logging is coming from (Log::Log4perl) which would serve to confuse rather than simplify.

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Re: using FATAL warnings
by ikegami (Patriarch) on Dec 16, 2009 at 18:31 UTC
    You could do 
    +    my $keyword = 0;
+    my $usage   = 0;
     foreach my $word ( @_ ) {
         if ($word eq 'FATAL') {
+            $usage ||= $keyword;
+            $keyword = 1;
             $fatal = 1;
             $no_fatal = 0;
         }
         elsif ($word eq 'NONFATAL') {
+            $usage ||= $keyword;
+            $keyword = 1;
             $fatal = 0;
             $no_fatal = 1;
         }
         elsif ($catmask = $Bits{$word}) {
+            $keyword = 0;
             $mask |= $catmask ;
             $mask |= $DeadBits{$word} if $fatal ;
             $mask &= ~($DeadBits{$word}|$All) if $no_fatal ;
         }
         else
           { Croaker("Unknown warnings category '$word'")}
     }
+    warn("No warning categories specified for FATAL or NONFATAL")
+        if $usage;

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    but it breaks backwards compatibility if someone does 
    use warnings FATAL => @fatals;

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    As such, this might be better off as a Perl::Critic check.

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[d/l]
[select]
Re: using FATAL warnings
by TGI (Parson) on Dec 28, 2009 at 19:31 UTC
[reply]

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