perlsyn says that in the when clause of a given block, or should cause "the test" to be applied recursively to the first argument. What happens to the second, then? Shouldn't the implicit smart-matching magic apply to both operands, as with and? I ran into this strangeness when I used something like given ($x) {when ('a' or 'b') {foo();}}, thinking it would work like foo() if $x ~~ 'a' or $x ~~ 'b'. Instead, it appears to be mysteriously inconsistent. The following code:

sub test
   {my $x = shift;
    given ($x)
      {when ('a' or 'b') {say 'Y';}
       default {say 'N';}}
    given ($x)
      {when ('a' or $_ ~~ 'b') {say 'Y';}
       default {say 'N';}}
    given ($x)
      {when ($_ ~~ 'a' or 'b') {say 'Y';}
       default {say 'N';}}}

test('a');
test('b');

[download]

prints:

Y
Y
Y
N
N
Y

[download]

Can anyone explain this? I'm using a perl version 5.10.0 that I built for i686-linux-thread-multi-ld, if it makes a difference.

In reply to Odd behavior of given {when (... or ...) ...} by Polynomial

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