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From: Marek Novy <novy1@odysseus.zcu.cz>
Newsgroups: comp.lang.beta
Subject: Re: Overriding procedural patterns
Date: 17 May 1995 10:18:18 GMT
Organization: Technical University of Ostrava, Czech Republic
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rws@daimi.aau.dk (Rene Wenzel Schmidt) wrote:

[stuff deleted]

>Code for e: (no change form current implementation)
>
>Me: putCharE
>    jump-subrutine [IDT+0]    ; IDP is a register pointing to the
>    return                    ; INNER dispatch table
>
>Code for f:
>
>Mf: putString
>    jump-subrutine Me         ; OUTER: Jumps directly to code for e
>    jump-subrutine [IDT+1]    ; INNER: standard code. The offset is
>                              ; 1 because it is the second INNER

Why can't it be [IDT+0]. It will have always same value. Every ':!' can
decrease the usual size of IDT by one.

>    return
>
>Code for g:
>
>Mg: putCharG
>    return
>
>The virtual-dispatch table for a call of G will have two
>entries because there is two INNERs. Both of the entries
>will point to Mg.
>
>IDTg:  .word Mg
>       .word Mg
>
>A call of g will be translated into to:
>
>load   IDT,IDTg
>jump-subrutine Mf

Also speaking to Erik. What do you say to that:

<new-pattern>:<structural-ancestor>!<functional-ancestor> (# ..... do
<over>;#);

where: Object >= 'functional-ancestor' >= 'structural-ancestor'
So it means the 'over' will be bound to the 'functional-ancestor' inner.
Outer has similar meaning, it directly calls imperatives replaced by over. Also
inner is similar, it calls indirectly imperatives of a functional descendant.

Limit cases:

B:A!A(#....#); is equal to usual B:A(#....#);
C:A!Object(#....#); is equal to Erik's C:!A(#....#);

Implementation is straightforward using inner dispatch table.
Is it right?
--
Marek Novy, University of West Bohemia
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Look at BatOS. A new approach to object OS : http://ody.zcu.cz/~novy1