Path: utzoo!attcan!uunet!snorkelwacker!usc!wuarchive!udel!new
From: new@udel.EDU (Darren New)
Newsgroups: comp.lang.misc
Subject: Re: Languages that allow extensions to classes
Message-ID: <16641@estelle.udel.EDU>
Date: 12 Apr 90 12:38:44 GMT
References: <16560@estelle.udel.EDU> <1238@fs1.ee.ubc.ca> <22413@cs.yale.edu>
Reply-To: new@ee.udel.edu (Darren New)
Organization: University of Delaware
Lines: 27

In article <22413@cs.yale.edu> briscoe-duke@CS.YALE.EDU (Duke Briscoe) writes:
>I think the other issue is whether a language has the capability of
>incrementally extending or redefining definitions without having to do
>massive recompilation.  

My original post which started this thread was meant to examine reusability.
My example is this:  I am working with a program called WISE, which is an
interpreter for a language called Estelle.  I am adding "hooks" into WISE
in order that at key points it calls my program (called GROPE).  When
new versions of WISE are released, I simply run the change manager
against all three versions and see what I've changed that the new
version also changed (actually, it's harder than that, but should be that
easy).  Given the old WISE, the old GROPE, and the new WISE, generating
the new GROPE is fairly simple.  Any changes to WISE that are not in the
area that GROPE changed do not need to be examined.  If I had to change 
all the header files for all the portions of the WISE system I extended,
these changes would have to be redone.  This problem is similar to
upgrading (say) a Unix system to a new release of the OS: you need
to save /etc/passwd, certain config stuff, /usr/local, and various other
files. You then install the new system and see what files you saved have
changed in the new system (new deamons in initrc that need to be run) and 
so on. Problematically, you MUST change distribution files in Unix in order
to configure your system.  I don't need to change distribution files in
Smalltalk in order to extend a system with a new capability.  The compilation
issue is less of a problem for me.  How about Ada?  I'm still not sure
whether all functions on a given type (or returning a given type?) must be
declared in the same header file.    -- Darren