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From: Andreas R. <and...@gm...> - 2004-04-08 16:05:47
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Hi Craig, > > What kind of method-lookup change? What is needed here... > > The current Squat implementation checks if the receiver's class is a > special "proxy" class (currently called "Other"), which is in the > special objects array. If it is, it kicks the send back to image, using > the same mechanism as for >>doesNotUnderstand:, so that the message may > be forwarded by the proxy. I'm missing something here - if it uses the same mechanism why would we need to change the lookup? Put differently, wouldn't it have the same effect if you just make Other a ProtoObject? Incidentally, talking about message forwarding. We might want to keep in mind the stuff that Stephen Pair did for the Chango VM - is he on this list? If not, we should invite him. He had some fairly interesting stuff going with delegation and that might be of some interest here. > > I'm slightly hesitent to reserve an object format for something like > > method dictionary marking. Can you elaborate on why this would be > > needed? > > The VM is the thing that does the activation marking. I'm using that > mark to tell when any method from a method dictionary has been run; it's > useful for, e.g., calculating which classes can be swapped out of an > image at some point in time. (There are also primitives for reading and > clearing the marks.) I'm missing something here too (guess I'll have to check the code). This sounds as if a method dictionary with an extra iVar or so would achieve the same effect at the same cost. > > ...we only have so many object format types. > > Well, the one I want to use (5) has gone unused for Squeak's entire > history, as far as I can tell. :) And it's not the only one (format 7 > is also unused). And in eight years I've yet to hear of anyone else > wanting one of them. :) And this is a very good cause. :) And I'm not > asking for any additional header bits. ;) (oops, smilie overload...) Oh, I'm not saying we shouldn't do this. I'm trying to understand if there is a "generalized benefit" from it, e.g., what else could one potentially do with these changes. > > Hm... something a little more specific would be nice ;-) > > 'Sorry, I was pressed for time (still am :). See > http://www.netjam.org/squat/releases/current/vmChanges.zip . Pick a VM > and snapshot from http://www.netjam.org/squat/releases/current/#theBits > to see the image side of things. Thanks, I'll check it out - guess that'll help with the above. Cheers, - Andreas |