On 18.07.2006, at 10:50, Marcus Denker wrote:

>
> On 18.07.2006, at 06:11, Chris Muller wrote:
>
>
> What I personally don't like is that blocks in Squeak mix the  
> static with the dynamic.
>
> For methods, we have the static (dead) description of  a method:  
> CompiledMethod.
> When it is run, a MethodContext is allocated. For blocks, we only  
> have the
> dynamic structure: BlockContext, even for the static structure of  
> "a Block".
>
> This is much nicer done in Anthony's design of blocks for the  
> ClosureCompiler.
>

As an example, have a look at a simple method accessing an iVar:

TT>>test
	^[i].

Then we execute:

TT new test explore

For the old compiler, this gets us a horribly complicated structure  
referencing
the Context of both the Block and the Method:

[] in TT>>test {[i]}
root: [] in TT>>test {[i]}
	sender: nil
	pc: 18
	stackp: 0
	nargs: 0
	startpc: 18
	home: TT>>test
		sender: nil
		pc: nil
		stackp: 0
		method: a CompiledMethod (2302)
		receiverMap: nil
		receiver: a TT


With the NewCompiler, the structure of the Closure is completely static,
it just references a method that encodes the code of the block and the
environment for the iVar access:

a BlockClosure (1599)
root: a BlockClosure (1599)
	method: a CompiledMethod (1605)
	environment: a TT
		i: nil

even with an outer temp reference, the picture does not get more  
complicated:

test
	| t |
	t := 5.
	^[t].

a BlockClosure (2739)
root: a BlockClosure (2739)
	method: a CompiledMethod (1814)
	environment: a ClosureEnvironment
		1: 5

The code of the method #test is compiled to reference the temp as the  
ivar in the Environment...
which is of course slowing down temp access for these kinds of shared  
temps.

     Marcus