In a recent post I noticed on_success => => sub { and thought, "huh, that's gotta hurt". To my surprise the extra => didn't have the effect I expected. I did a little experimenting:

use strict;
use warnings;

showParams(fat => => 'comma');
showParams('real', , 'comma');
showParams('explicit', undef, 'comma');

sub showParams {
    my @params = @_;

    for my $param (@params) {
        if (!defined $param) {
            print ">undef<\n";
            next;
        }

        if (ref $param) {
            print "'", ref $param, "'\n";
            next;
        }

        print "'$param'\n";
    }

    printf "\n";
}
[download]

Prints:

'fat'
'comma'

'real'
'comma'

'explicit'
>undef<
'comma'
[download]

I expected to see the >undef< line for each version of the call to showParams. What am I missing?

perl -v reports: This is perl 5, version 32, subversion 1 (v5.32.1) built for MSWin32-x64-multi-thread.