I am porting a Java class that calculates RealChallenge for RTSP. That package uses both Java operator >> and >>>. When I port it to Perl, I tried overloading. But I came to some questions.

I can mimic >> and >>> easily with use integer:

use strict;
use warnings;

print unsigned_shift(-4, 2), "\n";
print signed_shift(-4, 2), "\n";
print unsigned_shift(-4, 2), "\n";
print signed_shift(-4, 2), "\n";
print unsigned_shift(-4, 2), "\n";
print signed_shift(-4, 2), "\n";

sub signed_shift {
    use integer;
    return $_[0] >> $_[1];
}

sub unsigned_shift {
    return $_[0] >> $_[1];
}
[download]

But the following does not work, but gives no warning/error. I guess you cannot overload core function, or did I do soemthing wrong?

use Data::Dumper;

use strict;
use warnings;

use overload '>>' => \&singed_shift;
#use overload 'main::>>' => \&singed_shift;
#print Dumper(\%OVERLOAD);
print -4 >> 2;

sub signed_shift {
    use integer;
    return $_[0] >> $_[1];
}
[download]

I can put this in a package which will work:

package Number;

use strict;
use warnings;

use overload '>>' => \&signed_shift;

sub new {
    my $self;
    $self->{"number"} = $_[1];
    bless $self;
    return $self;
}

sub signed_shift {
    my ($self, $n) = @_;
    use integer;
    return ($self->{"number"} >> $n);
}

1;

use Data::Dumper;
use Number;

use strict;
use warnings;

my $n = new Number(-4);
print $n >> 2;
[download]

The other question is whether I can "overload" an operator that does not exist. for example whether I can '>>>' => \&blah. When I tried it, it didn't work (didn't like >>>). I don't think I can do that.

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