Re: Re: The world is not object oriented

Yes, that's how polymorphism is implemented in C++. But it doesn't have to work like that. Perl's bless'd objects, for instance, does polymorphisim by walking the inheirtance tree (not that this is a great way to do it--it's slow).

No. The inheritance tree is called that, because it is used for implementing inheritance, not polymorphism. Polymorphism means you have several things, that you can treat in a uniform way, for example because they all implement the same interface. Polymorphism is (for example) usefull, when you are storing objects in a container, and the container somehow has to interact with its objects.

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
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Re: Re: Re: The world is not object oriented by hardburn (Abbot) on Jan 02, 2004 at 16:34 UTC
The inheritance tree is called that, because it is used for implementing inheritance, not polymorphism. Polymorphism means you have several things, that you can treat in a uniform way, for example because they all implement the same interface. Subclasses, in general, have the same interface as their parents, which means that polymorphism and inheirtance are tightly bound. ---- I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident. -- Schemer `: () { :\|:& };:` Note: All code is untested, unless otherwise stated	[reply] [d/l]
Re: Re: Re: Re: The world is not object oriented by chromatic (Archbishop) on Jan 02, 2004 at 17:30 UTC
Yes and no. It's exceedingly difficult to have inheritance without polymorphism but it's exceedingly useful to have polymorphism without inheritance. Polymorphism is the principle. Inheritance is one application.	[reply]


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