For scoping reasons, I would change: 
sub switch{ eval{ goto "case_$_[0]" } or goto default; }

for my $expr ( 1 .. 10, 'fred' ) {
    switch( $expr ); {

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to: 
my $switch = sub { eval{ goto "case_$_[0]" } or goto default; };

for my $expr ( 1 .. 10, 'fred' ) {
        $switch->( $expr ); {

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but other than that, I must say I like this idiom as well. If you're not interested in performance, that is. Because the performance of the switch like this, is abysmal compared to an identical if/elsif/else structure, as this little benchmark shows: 
use strict;
use Benchmark;

timethese( 50000,{
 switch => sub {
sub switch{ eval{ goto "case_$_[0]" } or goto default; }

for my $expr ( 1 .. 10, 'fred' ) {
        switch( $expr ); {
                case_1:         print STDERR '1'; last;
                case_2:            print STDERR '2'; last;
                case_3:         print STDERR '3'; last;
                case_4:         print STDERR '4'; last;
                case_5:         ;
                case_6:         print STDERR '5 or 6'; last;
                case_fred:       print STDERR 'fred'; last;
                default:          print STDERR "default";
        }
}
},

 if => sub {
for my $expr ( 1 .. 10, 'fred' ) {
        if ($expr eq '1') {print STDERR '1'}
        elsif ($expr eq '2') {print STDERR '2'}
        elsif ($expr eq '3') {print STDERR '3'}
        elsif ($expr eq '4') {print STDERR '4'}
        elsif ($expr eq '5' or $expr eq '6') {print STDERR '5 or 6'}
        elsif ($expr eq 'fred') {print STDERR 'fred'}
        else {print STDERR "default"}
}
},
} );

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Please note that I changed the print statements to "print STDERR" so that I could send them to the bitbucket. The result of the benchmark: 
Benchmark: 
timing 50000 iterations of
 if, switch
        if:  7 wallclock secs ( 5.41 usr +  0.00 sys =  5.41 CPU) @ 92
+42.14/s (n=50000)

    switch: 43 wallclock secs (39.85 usr +  0.00 sys = 39.85 CPU) @ 12
+54.71/s (n=50000)

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So the switch structure is at least 7 times as a comparable id/elsif/else structure. So don't put this in very deep and tight loops!

Liz

Edit by tye, change PRE to CODE around long lines

In reply to Re: Re: Simple Switch statement by liz
in thread Simple Switch statement by knexus

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