in reply to Re^3: Smart enough for Smart Match??? (was "Understanding ...Given/When" )
in thread Understanding the benefit of Given/When ...

extending your code shows that there is a bug when matching ARRAY ~~ REGEX, do you agree?

use 5.010;
use strict;
use warnings;
 
my @a=('abc',1);
given (@a) {
    when (/abc/  ) { print '/abc/'."\n" ;continue}
    when ("abc"  ) { print "abc\n" ;continue}
    #when (1      ) { print "#\n"   ;continue}
    when (['abc',1]) { print "copy\n" ;continue}
    when (\@a    ) { print "self\n" }
}
 
print "as it should be: ",@a~~/abc/;

[download]

OUTPUT 

abc
copy
self
as it should be 1

[download]

Cheers Rolf

PS: I have to go, too ...

Replies are listed 'Best First'.
Re^5: Smart enough for Smart Match??? (was "Understanding ...Given/When" )
by ikegami (Patriarch) on Mar 04, 2010 at 19:08 UTC
    You need to do when (qr/abc/). when(/abc/) appears to do when($_ ~~ ($_ =~ /abc/)). 
    use 5.010;
use strict;
use warnings;

my @a=qw(abc def);

given (@a) {
    when (/abc/  ) { say '/abc/';   continue; }
    when (qr/abc/) { say 'qr/abc/'; continue; }
}

say '--';

if (@a ~~ /abc/  ) { say '/abc/';   }
if (@a ~~ qr/abc/) { say 'qr/abc/'; }

    [download]
    qr/abc/
--
/abc/
qr/abc/

    [download]
    The discrepency is odd, though.
[reply]
[d/l]
[select]
      But it is documented.

      But when EXPR is one of the below exceptional cases, it is used directly as a boolean:

      • [...]
      • a regular expression match, i.e. /REGEX/ or $foo =~ /REGEX/, or a negated regular expression match (!/REGEX/ or $foo !~ /REGEX/).
      • [...]

      It makes sense. It allows 

      given ($x) {
   when (/abc/) { ... }
   when (/def/) { ... }
   when (/ghi/) { ... }
}

      [download]

      to mean 

      if    ($x =~ /abc/) { ... }
elsif ($x =~ /def/) { ... }
elsif ($x =~ /ghi/) { ... }

      [download]
[reply]
[d/l]
[select]
        What...

        OMG it took me a while to understand it ... yes it makes sense:

        use 5.010;
use strict;
use warnings;
 
my @a=('abc');
given (@a) {
    print "$_\n";
    when (/ARRAY/  ) { print "ARRAY\n" ;continue}      # regex-match!
    when (/abc/  ) { print '/abc/'."\n" ;continue}     # no match
    when (qr/abc/  ) { print 'qr/abc/'."\n" ;continue} # smart-match!
}

        [download]

        OUTPUT: 

        ARRAY(0x8255a70)
ARRAY
qr/abc/

        [download]

        Sigh ... do you agree that the docs could be more explicit? :)

        Cheers Rolf

[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom