On 29-Jan-06, at 9:35 PM, Andreas Raab wrote:

> tim Rowledge wrote:
>> On 29-Jan-06, at 10:58 AM, Andreas Raab wrote:
>>> Fixing this will not be easy - if a VM change is required it  
>>> means  that older images will fail on newer VMs and vice versa.
>> Ah, well, not absolutely definite. It's tacky but one could make a  
>> vm  that works out the offset to the class name and uses a var  
>> from then  on.
>
> You mean searching the iVars of a well-known class (like Point) for  
> the string "Point"? Yes, that would work. Very clever. And very  
> tacky ;-)
Sometimes tacky is all that saves you. Remember, we carefully collect  
tacky and spread it onto strips of fabric and call it duct tape.  
Doesn't come much more useful than that.

A cleaner interface for the future that would allow for changing the  
ivar layout of behaviour (and by extension do the same for object if  
really needed) would be a prim that tells the vm the right offset.  
There would be some interesting times if there were a problem before  
that prim had run of course. Done well it could allow the layout to  
change whilst running the image, which might be useful in a hyper- 
expanding system like Spoon.


tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
Useful random insult:- Permanently out to lunch.