Context of Execution

[Brian Rice]

On Jul 22, 2006, at 1:42 PM, Jack Waugh wrote:

> Does the language definition require that every invocation of a  
> method or block
> happen with a new context?  Must the context inherit from the  
> calling context?

Huh? What do you mean by a "context"? A stack frame, perhaps? The  
compiler determines whether it can execute a lexical (literal) block  
in a method as a piece of bytecode or whether a separate Method  
object must be created and then run in a separate stack frame. src/ 
mobius/vm/interp/compiler.slate has the details. Since Slate is  
lexically-scoped, then of course it's implicit that contexts inherit  
from the lexically-enclosing scopes.

> Where is the source code to the macro, "`>>"?

src/lib/macro.slate which has the documentation for it. (Grepping  
"@.*>>" will find it for you).

>   Doesnt' "`>>" pass an arbitrary
> object (its left argument) as the context?

It takes an expression which `>> when expanded is evaluated and  
possibly stored for a bunch of following statements to act on in the  
left-most argument position.

>   Does that break programmers'
> expectations about what the context does for its callers?

What expectations are those?

>   Does it cut off
> access to the lobby, for example, for the code in the block that is  
> the right
> argument of "`>>", and for code called by that code?

No, the lobby or other scope can be accessed if using parentheses to  
change the precedence ordering of evaluation.

Incidentally, `>> [] is merely notation to not require Smalltalk-80's  
";" special cascade operator.

--
-Brian
http://tunes.org/~water/brice.vcf

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