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Path: utzoo!watmath!clyde!rutgers!brl-adm!seismo!mcnc!unc!rentsch
From: rentsch@unc.UUCP
Newsgroups: comp.lang.misc
Subject: More on unbounded polymorphism
Message-ID: <924@unc.unc.UUCP>
Date: Sun, 15-Feb-87 04:42:22 EST
Article-I.D.: unc.924
Posted: Sun Feb 15 04:42:22 1987
Date-Received: Tue, 17-Feb-87 05:52:35 EST
References: <4000001@nucsrl.UUCP> <3288@milano.UUCP>
Reply-To: rentsch@unc.UUCP (Tim Rentsch)
Organization: CS Dept, U. of N. Carolina, Chapel Hill
Lines: 19
Summary: Another unbounded polymorphism example

In article <540086280.7983@minster.UUCP> martin@minster.UUCP (martin) writes:
> Maybe not a queue... But I can certainly think of a dictionary, the elements
> of which I might want to be absolutely anything. That is the Smalltalk
> system dictionary!! I want this to be able to contain references to
> any object in the system, biteditors, windows, processes etc.
> 
> Of course I don't need, but would also like, the same freedom on
> the types of the keys!

Good example.

To add to the example, remember that (in Smalltalk-80, at least)
'Dictionary' is a subclass of 'Set' (which is a subclass of
'Collection').  So, whatever polymorphism is needed from Dictionary
is also needed from Set (and Collection, etc.).

cheers,

Tim