On Thu, Jan 13, 2011 at 2:06 AM, Martijn van Oosterhout
<kleptog@svana.org> wrote:
> I played with this a little and it is fairly easy to make a variable
> such that $a is the string representation and $a[0] the first value of
> the array. The problem is that you can't pass such a variable into a
> subroutine.
I played with this too:
#!/usr/bin/perl -w
use strict;
package Pg::ArrayArg;
use overload '""' => \&as_s, '@{}' => \&as_a;
sub new { my $proto = shift; my $class = ref $proto || $proto;
bless { string => shift, array => shift }, $class;
}
sub as_s { shift->{ 'string' };
}
sub as_a { shift->{ 'array' };
}
package main;
my $aa = Pg::ArrayArg->new( '{1,2}', [ 1, 2 ] );
printf "ref = %s\n", ref $aa;
print "string = $aa\n";
printf "string = %s\n", $aa;
printf "array index = (%s, %s)\n", $aa->[ 0 ], $aa->[ 1 ];
printf "array_ref = %s\n", scalar @$aa;
print "regexp test = ";
if ($aa =~ /^{(.*)}$/) { print "looks like array\n"; printf "join of split = %s\n", join ';', split /,/, $1;
} else { print "doesn't look like array\n";
}
Suppose one of these compatibility objects is passed into legacy code
as $_[0]. The problem is that 'ref $_[0]' will return 'Pg::ArrayArg'
instead of what it used to, '' (empty string). Other than that, I
think it performs as people would expect.
You could even change 'as_s' to generate the string on the fly as
requested instead of generating both representations at instantiation.
Just my $0.02.
