[REBOL] context of a function Re:(4)
From: fsievert:uos at: 22-Aug-2000 21:10
On Mon, 21 Aug 2000 [rebol--techscribe--com] wrote:
> Hi Frank,
>
> I think you are speaking about three distinct, albeit related tasks:
>
> 1. Determining which words are bound to the context of a function.
> 2. Binding words that are bound in the context of a function to that context.
> 3. Determining which values these words are associated with.
Thats absolutely right.
> Re 1:
> You can easily determine which words are bound to the context of a function
> by retrieving the first or third block of a function.
No, thats not possible. Example:
>> f: func [a] [a]
>> make object! [a: none insert second :f 'a]
There is no way to find out, which of the a's is the one, which is bound
to functions context now.
> With exception of /local all of these words are bound to the function's
> context, as soon as the function is constructed.
Local (as a word) is, too.
> Re 2:
> You can easily bind the words in the function's first or third block to the
> function's context:
>
> >> bind fblock first second :f
> == [a ref b]
Not possible here:
f: func [a] []
No word example -> no way to say bind. That s why we need in for
functions.
> Re 3:
> You can now easily determine which values the words are associated with in
> the function's context:
Same problem as above.
> Conclusion:
> This approach only works if there is at least one word that is local to the
> function's context available at a known index in the function's body. In
> this example it was the word "a" in the first position in the function's body.
You could overwrite func, but I think, REBOL should support this. Its the
same as in objects.
To serialize functions like shown above (the one with the two a's), you
need a way to find out, which of the a's are bound to functions body and
which not. I would like to use "in" for that, which would be the same
sollution as for objects.
Greetings,
Frank
