[REBOL] Re: Binding
From: robert:muench:robertmuench at: 20-Nov-2002 9:36
> -----Original Message-----
> From: [rebol-bounce--rebol--com] [mailto:[rebol-bounce--rebol--com]]
> On Behalf Of Carl at REBOL
> Sent: Wednesday, November 20, 2002 1:06 AM
> To: [rebol-list--rebol--com]
> Subject: [REBOL] Re: Binding
> Exactly. It has to be that way. Here's an example of why:
>
> print-block: func [block] [
> foreach value reduce block [
> print value
> ]
> ]
>
> example: has [temp][
> temp: 12
> print-block [temp now]
> ]
>
> The contexts of TEMP and NOW have to be carried with them,
> otherwise they can not be known within the print-block.
Hi, I understand this but it's really different to compiled languages.
In a compiled language this would be called "call-by-reference". BTW:
Are there are any situations where Rebol makes an implicit copy of words
where I loose this "by-reference" semantic?
> This is that "variation" on static (syntactic)
> binding that REBOL uses. It's not precisely static, because
> it can be modified at runtime by functions like BIND, MAKE, FUNC, etc.
And that's what IMO is what "normal" programmers have the biggest
problem with. In C++ a variable name and value is a unit. And if you
don't change the value it won't change (only if you leave a scope). In
Rebol a "variable" (a.k.a word) is just a human-readable-descriptor so
that we can write it down. The value of such a word depends on the
binding, which is dynamic and context-dependent.
> BTW, named contexts *are* created by MAKE OBJECT...
Right, but at the moment these are more containers for words than
useable structures (first-class-object?)
> what you want is a way to pass them as an argument to BIND (rather
> than a word from the object). An interesting (and doable) idea.
Exactly! And if it's doable I highly vote for such a feature! And it
would be nice to be able to query the (named) context of a word for
debugging.
When can we see this feature? :-))) Robert
