in reply to Turn matching against undef to be deadly

use strict;
use warnings;
use Carp;


local $SIG{__WARN__} = sub {
if ($_[0] =~ /Use of uninitialized value in regexp compilation/) {
confess $_[0];
} else {
 warn @_;
}
};

print "x".undef, "\n";

printf "matched: %s\n"
  , ( 'x' =~ undef() ? 'yes' : 'no' )
    ;
__END__
Use of uninitialized value in concatenation (.) or string at 1.pl line
+ 14.
x
Use of uninitialized value in regexp compilation at 1.pl line 16.
 at 1.pl line 7.
        main::__ANON__('Use of uninitialized value in regexp compilati
+on at 1.pl line...') called at 1.pl line 16

[download]


pros: it works.

cons:
1. I think you should at least unit-test it, because warning format can change in different perl versions.
2. Dynamic scoped (this can be worked around with %^H, probably)

Replies are listed 'Best First'.
Re^2: Turn matching against undef to be deadly ( use warnings qw/ FATAL all /;
by Anonymous Monk on Sep 26, 2013 at 13:25 UTC
[reply]
[d/l]
Re^2: Turn matching against undef to be deadly
by Anonymous Monk on Sep 26, 2013 at 13:37 UTC

    Thanks, vsespb.

    The likelihood of change in warning and having to match against a string are the reasons why I forgot to mention about WARN signal as soon as I had thought about it before posting.

[reply]
      As another Anonymous Monk pointed above you can use warnings 'FATAIL' for all warnings or only "uninitialized". Lexical scope used. But this will catch other types of "uninitialized" warnings. 
      use strict;
use warnings;
use Carp;
use warnings FATAL => 'uninitialized';
printf "matched: %s\n"
  , ( 'x' =~ undef() ? 'yes' : 'no' )
    ;

print "end\n";

      [download]
[reply]
[d/l]

        See perllexwarn for all the warnings that can be turned into FATAL-ities, etc.     (Update: Oops — didn't notice Anonymonk already linked these!)

[reply]
[d/l]

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