How can I call methods on Perl scalars?

Question

I saw some code that called methods on scalars (numbers), something like:

print 42->is_odd

What do you have to overload so that you can achieve this sort of "functionality" in your code?

score 10 · Accepted Answer · edited May 23 '17 at 12:13

10

Are you referring to autobox? See also Should I use autobox in Perl?.

edited May 23 '17 at 12:13

Community

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answered Nov 25 '09 at 21:44

Ether

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it's one module I noticed. another one could be `scalar::object`. I saw that `autoload` uses XS, and I noticed `scalar::object` doesn't. I'd rather be more interested in the way `scalar::object` does it's thing. I'm curious if this can be done without resorting to lower level programming. – Geo Nov 25 '09 at 22:00
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`scalar::object` uses `overload::constant` and other `overload` magic, but it also doesn't have nearly the power `autobox` does. `autobox` works by hooking into the implementation of the `->foo()` method call operator itself. – hobbs Nov 25 '09 at 22:19
autobox certainly is the way to go for this kind of functionality. – tsee Nov 26 '09 at 09:06

score 1 · Answer 2 · answered Nov 26 '09 at 11:57

This is an example using the autobox feature.

#!/usr/bin/perl

use strict;
use warnings;

package MyInt;

sub is_odd {
  my $int = shift;
  return ($int%2);
}

package main;

use autobox INTEGER => 'MyInt';
print "42: ".42->is_odd."\n";
print "43: ".43->is_odd."\n";
print "44: ".44->is_odd."\n";

How can I call methods on Perl scalars?

2 Answers2