At 8:00 AM -0700 on 12/3/99, Rob Cozens wrote:
>A few thoughts beyond my original "how can I do without those capabilities?":
>
>* Anthony, is this because --
>
> A. The capabilities would be inefficient if implemented,
> B. Implementation of these capabilities would negatively impact overall
>performance (eg: implementing send slows all message passing), or
> C. Something else (please explain)?
A & B definitely apply. C also does -- it would be hard as hell to get them
into the interpreter.
I'll try and explain why. The interpreter is not a classical interpreter at
all. It is more accurately a compiler and an emulator joined together. I'll
give an example, as it will apply to the new interpreter. Remember that the
new interpreter does not yet exists, so this is a just a plan. But the old
interpreter works in a very simular way. Take an example script:
function x a,b
put a*(b+2*a) into c
answer c with "OK" or "Cancel"
return it
end x
This will be passed to the parse, then to the tokenizer, then to the
compiler, which will spit out:
; Take note! The numbers refer to variables (unless proceeded by a
; number sign). Variables are as follows
; (this is not acutally part of the compiler output!)
;
; a = 0
; b = 1
;
; I'm inserting these comments to make it easier to read
pop 1 ; load parameters into variables
pop 0
load 2, #2 ; TMP1 = 2
mul 3, 2, 0 ; TMP2 = 3
add 2, 1, 3 ; TMP1 re-used; TMP2 now unused
mul 2, 0, 2 ; WATCH OUT! TMP1 is now c.
push 2 ; Push c, begin call to answer
push.s 0 ; String table entry 0, "OK"
push.s 1 ; String table entry 1, "Cancel"
call 2 ; String table entry 2, "answer"
end ; return. Don't need to push result onto stack
; because answer already did that.
You'll notice that there is about no way to get a 'do' command, a
runtime-named variable, etc. into that. It is possible, however, to use
hashes for the runtime-named variable effect. And hopefully, NuTalk will be
powerfull enough you won't need a do command.
I don't mind code written at runtime; I do mind it sharing environment with
the code that writes it. If you want a do command like a function call
(i.e., respects local variables), fine, that's doable.
