Test

test_roles.pl

#!/usr/bin/env perl

test_smartmatch.pl

#!/usr/bin/env perl

use 5.10.0;

my $n = 42;

given (eval $ARGV[0]) {
    when (eval $ARGV[1]) {
        say "MATCH!";
    }
    when (sub { $_->value eq "x" }) {
    }
    default {
        say "NOPE";
    }
};

package My;
use YAML::XS;
use overload
    '~~' => sub { say Dump @_; return '' },
    '""' => sub { __PACKAGE__ },
    fallback => 1;
sub new { bless {} => shift };
sub value { 42 };

test_smartmatch2.pl

#!/usr/bin/env perl

use 5.10.0;

given (eval $ARGV[0]) {
    when (eval $ARGV[1]) {
        say "MATCH!";
    }
    default {
        say "NOPE";
    }
};

package My;
use YAML::XS;
use overload
    '~~' => sub { say Dump @_; return '' },
    '""' => sub { __PACKAGE__ },
    fallback => 1;
sub new { bless {} => shift };