Re: RfD - Enhanced local variable syntax (long)

Stephen Pelc wrote:
> At long last I've started on my Forth200x tasks. Here's the first
> cut of the enhanced local variables using the { ... } notation.
>
> Stephen
>
> RfD - Enhanced local variable syntax
> ====================================
> Stephen Pelc - 20 August 2006
>
> Problem
> =======
> 1) The current LOCALS| ... | notation explicitly forces all locals
> to be initialised from the data stack.
> 2) 1) The current LOCALS| ... | notation defines locals in reverse
> order to the normal stack notation.
> 3) When programming large applications, especially those interfacing
> with a host operating system, there is a frequent need for tem****ary
> buffers.
> 4) Current implementations show that creation and destruction of
> local buffers are much faster than using ALLOCATE (14.6.1.0707)
> and FREE (14.6.1.1605).
>
> Solution
> ========
> Base version
> ------------
> The following syntax for local arguments and local variables is
> proposed. The sequence:
>   { ni1 ni2 ... | lv1 lv2 ... -- o1 o2 }
> defines local arguments, local variables, and outputs. The local
> arguments are automatically initialised from the data stack on
> entry, the rightmost being taken from the top of the data stack.
> Local arguments and local variables can be referenced by name within
> the word during compilation. The output names are dummies to allow
> a complete stack comment to be generated.
>   The items between { and | are local arguments.
>   The items between | and -- are local variables or buffers.
>   The items between -- and } are outputs.

[snip]

Intersting. I've been slowly working on a Forth-based lanaguage in
which I aquire local variables using slightly different notation. To
reuse your example, essentially:

 : foo
   'b 'a
   a' b' + 'a+b
   a' b' * 'a*b
   cr a+b' .  a*b' .
 ;

Such that 'var pops the value off the stack and stores it. And var'
puts the value (or actually a reference to the value) back onto the
stack. Yes, the initial stores are backward but I don;t find that too
problematic.

I have not consider the treatment of fixed sized buffers however.

~Trans.

P.S. I am still relatively new to Forth.