I'm not suggesting that you actually use this, but the following is a simple implementation of the :zero (here :ZeroDefault) attribute. It's intended to show you that what you would like to have is quite easy to implement in pure Perl without changing the interpreter at all or writing a single line of XS/C. All the usual attribute-gotchas apply. All the usual tie() gotchas apply, too. (Slowness, for example.)
#!/usr/bin/perl
use 5.006;
use strict;
use warnings;
package Attribute::Array::Zeroes;
use Tie::Array;
use base 'Tie::StdArray';
use Attribute::Handlers autotie => {
'__CALLER__::ZeroDefault' => 'Attribute::Array::Zeroes'
};
sub FETCH {
my $return = $_[0]->[$_[1]];
return 0 if not defined $return;
$return;
}
package main;
#use Attribute::Array::Zeroes;
my @x : ZeroDefault;
print "This is zero, not undef: $x[4]\n";
$x[5] = 1;
print "This, too: $x[0] and even this: $x[6]. This isn't: $x[5]\n";
Of course, this is just a hack and I haven't tested it thoroughly. Cheers, Steffen
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