[REBOL] Re: The truth about scope
From: mokkel:gmx at: 16-Apr-2005 11:37
Hi Volker,
> About
> bind bl in c 'a
> Actually the value has a place!
> Because 'bind has a return value ;)
Yes I know, I just first wanted to complain (note) that it's kind of
awkward that one can't bind a single word in-place (bind 'a in c 'a). The
'a after the 'bind won't be changed. In the case of the "picking it out of
a block" this looks to me quite naturally as I (one) decided what word to
rebind (if one want's to bind a whole block it will always bind all words,
but what if there are some words which shouldn't be bound - might be a bit
constructed case nevertheless). So I just though would be good to check it
against the model, whether it makes actually sense to try to do so. And
then the observation was that because value-slots are copied (shallow),
there is no way to reference a certain word, the spelling simply get's
copied and thus there is no way to pick (and designate) a word out of a
block, which will be changed. We will only get another "instance" of the
word and if we 'get it, it referes to the value-slot in its according
context-table.
So in case of single words, bind has to return another word as
return-value, that in case of a block it is returned also, is just
consistency I guess. :-)
I also haven't been too exact about the representation of block references
in-code/data. Actually it should have been looked always like:
a: 5
bl: [a "hallo" 1]
->
(bl:) (|,1)
|
(a)-(|,1)-(1) ; real value-slot list
| |
(5) |
(h)-(a)-(l)-(l)-(o) ; this are actually no real (I guess)
value-slots any-more
I usually only wrote
(bl:) [(a) (|,1) (1)] .......
Thanks for taking a look at it.
Regards
Michael
