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Postings from April 2000
Here's a possible solution for "overloading" =, in scalars.
# file: test
use Tie::AssignWrapper;
use Example;
tie $foo, 'Tie::AssignWrapper', 'Example', 100;
print $foo - 5, $foo, $foo + 5;
$foo = 25;
print $foo - 2, $foo, $foo + 2;
# file: Tie/AssignWrapper.pm
package Tie::AssignWrapper;
sub TIESCALAR {
my ($class,$module,$value) = @_;
my $self = [ $::{"${module}::"}, $module ];
$self->[2] = $self->[0]{__store}->($value);
return bless $self, $class;
}
sub FETCH {
my $self = shift;
return bless \$self->[2], $self->[1];
}
sub STORE {
my ($self,$value) = @_;
return bless \($self->[2] = $self->[0]{__store}->($value)), $self->[1];
}
1;
# file: Example.pm
package Example;
use overload (
'+0' => \&__fetch,
'""' => \&__fetch,
fallback => 1,
);
sub __fetch { ${+shift} }
sub __store { sqrt(shift) }
1;
Questions? Comments? Concerns? Flames?
--
MIDN 4/C PINYAN, NROTCURPI, US Naval Reserve japhy@pobox.com
http://www.pobox.com/~japhy/ http://pinyaj.stu.rpi.edu/
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