[Vm-dev] Re: SmallInetger as methods was not ready yet....now maybe?

[Andreas Raab]

On 12/3/2010 4:18 PM, Eliot Miranda wrote:
> BTW, Mariano's use of SmallIntegers rather than wrappers is an attempt
> to get a very compact image and seems a reasonable experiment.  Using
> wrappers would defeat his use-as-little-memory-as-possible purpose.

Not at all. The design of objects-as-methods was deliberately done such 
that one could use a single wrapper for multiple methods. The only thing 
you need is to map from selector to method being executed. For example:

MethodSwapper>>run: aSelector with: argsArray in: aReceiver
	"Execute the given method"
	method:= methodMap at: aSelector.
	^aReceiver withArgs: argsArray executeMethod: method

Then you install a single MethodSwapper instance like here:

swapper := MethodSwapper new.
Morph selectorsAndMethodsDo:[:sel :meth| swapper methodMap at: sel put: 
meth].
Morph selectorsDo:[:sel| Morph addSelector: sel withMethod: swapper].

At this point the only overhead you have is what's in the (single) 
MethodSwapper instance and even with a most naive implementation 
(looking up the index by selector) you'd have 8 bytes per method in your 
image which I suspect is well below 5% of the image size.

And then of course you can start *really* looking at getting the size 
down. Did you know that Dan once did a very neat hack where he replaced 
all symbols with integers? Works great and if you do that you not only 
reclaim the space for the symbols but also don't need a lookup at all :-)

Cheers,
   - Andreas