Objective-C Issues

smalltalk

People ( From: lines )
 michael@stb.info.com (Michael Gersten)
 Steve_Naroff@next.com (Steve Naroff)
Subjects ( 3 mails )
 Smalltalk
 Re: Automatic input/output, persistence
 Auto persistance of objects: A comprimise
Document
Date: Wed, 16 Sep 92 14:31 PDT
From: michael@stb.info.com (Michael Gersten)
To: Geoffrey S. Knauth 
Subject: Smalltalk

Actually, not smalltalk, but a language called Actor on the IBM PC
under windows.

Roughly, Actor is based on smalltalk, and inspired by it; the core of
the language is a forth engine, highly optimized for accessing
instance variables of objects and elements of an array. (In fact,
there's no difference between accessing the nth element of an array
object, or the nth instance variable of other objects after the
compiler has gotten through with it. Of course, a class can either
have instance, or indexed variables, but not both).

The scheme I described is very similar to what Actor uses, but does
not go into the specifics and details. (Lets say I'm worried about
"contaminating" the list and opening the FSF to a lawsuit).

		Michael
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		Michael Gersten		michael@stb.info.com
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From Steve_Naroff@next.com Wed Sep 16 19:35:55 1992
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From: Steve_Naroff@next.com (Steve Naroff)
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Date: Wed, 16 Sep 92 16:17:55 -0700
To: dennis_glatting@trirex.com
Subject: Re: Automatic input/output, persistence
Cc: uunet!lehigh.edu!gdb0@uunet.uu.net (GLENN BLANK), gnu-objc@prep.ai.mit.edu


> Shouldn't the object itself be responsible for what it contains and what is 
relevant rather than an outside entity? 

Absolutely...here are three reasons that come to mind:

1) Control over what is persistent (vs. transient). This feature can dramatically 
   effect the size of the composite object (and associated cost to activate it from 
   disk).
2) Data that needs to be converted on read/write (e.g. ports, file descriptors...
   i.e. any data that has different meanings across process boundaries).
3) Version control for converting old objects to new objects...the object 
   database folks call this "schema evolution" (sounds fancy). NeXTSTEP objects 
   can read old versions of themselves without any problem...we don't force the 
   application to evolve all nib files in concert. This flexibility is very hard 
   to achieve without involving the object.

Schemes that do not have these capabilities are usually not very useful for 
building real applications.

snaroff

From stb!michael@cs.ucla.edu Wed Sep 16 23:33:21 1992
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Date: Wed, 16 Sep 92 19:38 PDT
From: michael@stb.info.com (Michael Gersten)
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To: ucla-cs!prep.ai.mit.edu!gnu-objc@cs.ucla.edu
Subject: Auto persistance of objects: A comprimise

Here's a possible solution:

If you don't want Object to have a default way of reading and writting all 
objects, why not have some tool that reads a .h file, and generates a read: 
and write: method to do default archiving?

This way all objects get one by default, and you can customize it if you want to.

		Michael
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		Michael Gersten		michael@stb.info.com
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Statistics
 filename:           smalltalk
 number of mails:    3
 number of writers:  2
 line count:         81
 word count:         474
 character count:    3294

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