[Vm-dev] Re: SmallInetger as methods was not ready yet....now
andreas.raab at gmx.de
Sat Dec 4 01:21:32 UTC 2010
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:
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 :-)
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