Re: Arbitrary mathematical relations, not just hashes

On Sun, 2008-04-06 at 16:52 -0700, Kelly Jones wrote: > Many programming languages (including Perl, Ruby, and PHP) support hashes: > > $color['apple'] = 'red'; > $color['ruby'] = 'red'; > > $type['apple'] = 'fruit'; > $type['ruby'] = 'gem'; > > This quickly lets me find the color or type of a given item. > > In this sense, color() and type() are like mathematical functions. > > However, I can't easily find all items whose $color is 'red', nor all > items whose $type is 'fruit'. In other words, color() and type() > aren't full mathematical relations. > > Of course, I could create the inverse function as I go along: > > $inverse_color['red'] = ['apple', 'ruby']; # uglyish, assigning > list to value > > and there are many other ways to do this, but they all seem kludgey. > > Is there a clean way to add 'relation' support to Perl, Ruby, or PHP? Yes, create a class/object to handle the relationship. That way, the details are hidden and may be anything you want. E.g. use Relationship; my $color = new Relatinship; $color->add( 'apple', 'red' ); $color->add( 'ruby', 'red' ); my $type = new Relationship; $type->add( 'apple', 'fruit' ); $type->add( 'ruby', 'gem' ); my @red_things = $color->find( undef, 'red' ); -- Just my 0.00000002 million dollars worth, Shawn 99% of you are just big dumb apes! +------------\ | Shangri La \ | 40,000 KM / +------------/