Good points.

Actually Simula I had by far the most influence early on (1966). 
Simula 67 had very little influence on most of the stuff from Flex 
onwards. By the time the documents arrived, alternates were well 
along. But I do remember thinking that the Simula folks had done a 
hell of a job with 67 -- It was a tremendous change and improvement 
from Simula I (but still with the monster type limitations that you 
refer to below).
      I did not like the inheritance scheme of Simula 67 (Simula I 
didn't have one), did not put it into ST-72 in the hopes that we 
would come up with something less spidery. Maybe the best alternative 
that didn't make it into later Smalltalks was a slot inheritance 
scheme worked out by Larry Tesler. I've never been in love with the 
ST-76 or -80 inheritance schemes -- I still like "sideways" schemes 
for having multiple centers of meaning for an object. Maybe we'll do 
a good one some day ...

Cheers,

Alan

-------

At 12:02 PM +1300 10/10/01, Richard A. O'Keefe wrote:
>Tim Rowledge <tim at sumeru.stanford.edu> wrote:
>
>	What? You mean that you have to do special work to be able to push
>	objects? Ludicrous! How could anybody live such a dumb restricion. Why,
>	that would be as dumb as integers and floats not being proper objects!
>
>Remember, this is talking about Simula >>67<<.  It was developed before
>"modals" were invented for Algol 68 (yes, I know they aren't in Algol 68,
>but they were invented _for_ Algol 68 and described in the Algol Bulletin).
>Hindley-Milner type checking and Eiffel were as yet undreamed of.
>
>If you're going to develop a type-safe single-inheritance OO language
>starting from an Algol 60 base and have never seen parametric polymorphism,
>you are going to end up with something very like Simula, complete with
>the restriction that objects can only go into a scheduling set (a real
>example from Simula 67) if they belong to a class that was declared to
>inherit from the appropriate scheduling set element class.
>
>Smalltalk's main improvements to Simula 67 amount to removing things.
>(Including restrictions.)


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