World: r3wp

Geomol, the reason you do that, is of course to avoid garbage collection 
of said "locals"?

CONTEXT is a function, and you can see, what it does with:

>> source context

context is used for that purpose ?

context is just another word for "make object!"

ah ok.

and objects are contexts. when wrapping set-word!s in contexts, they 
stay inside that context.

Henrik, no, not really because of garbage collection, because the 
garbage collector doesn't collect words defined 'globally', right? 
I do it, because it's good programming practise to not have many 
globals. :-)

Henrik: that' seems a good way to handle namespaces ?

kib2, you'll find that many scripts come wrapped in contexts. this 
is the best we can do until R3 brings us modules. contexts are not 
waterproof, though.

context [
  a: 1 ; only inside context
  set 'b 2 ; global
]


This can be useful, if you want to create an object with one "public" 
function.

>> 3 + 2  == 5
>> 3x2 + 2x3 == 5x5

Geomol, true. In some extreme cases however, I've experienced crashes, 
because too much garbage collection happens. I always had to solve 
it by converting some locals to globals.

kib2, since you can bind contexts everywhere, even inside other contexts, 
they are not really secure and so you can't make things really private 
to a context. Modules will do that, I believe.

Henrik, ok got it. Well, in huge programs (like RPaint), I try to 
avoid garbage collection as much as possible. Garbage collection 
always works against performance, so it's bad in real-time applications 
(multi-media, games, etc.).

+ in this two cases "dispatches" on the type of arg... but this is 
probably handlede inside + , so if you define new type (vector3d) 
you couldn't make + work for that datatype too without changing it 
... in multiple dispatch + is a generic word and you add definitions 
for it for that datatype so it can work on them without changing 
or having access the original +  (basically similar to what is operator 
overloading at static lang, here it dispatches in runtime based on 
type)

Janko, I think you would solve that with typesets.

OTOH, maybe not. the function itself must support whatever argument 
is passed to it.

Is there any quickref card for Rebol somewhere ?

kib2: The word browser is pretty good. It's inside the Viewtop under 
REBOL/Tools, I think.

ok thanks!

Janko, I've been thinking about this problem too, and I'm not sure, 
what's best. Is it good enough, what we can do with functions today? 
Like:

>> old-add: :add

>> add: func [a b] [either string! = type? a [join a b] [old-add 
a b]]
>> add 4 5
== 9
>> add "Hi " "John"
== "Hi John"

Now ADD can also be used to join strings.

kib, I often use the REBOL dictionary: http://www.rebol.com/docs/dictionary.html

Geomol: that's exactly what I was looking for!

fictional example I made up:

make-type dog!
make-type cat!

make-generic 'say

say: func [ a [ dog! ]] [ "woof" ]
say: func [ a [ cat! ]] [ "meov" ]

or no.. say: woulnd't be good .. something like

Janko, yes, that would be cool to do.

make-type dog!
make-type cat!

make-generic 'say [ a [ dog! ]] [ "woof" ]
make-generic 'say [ a [ cat! ]] [ "meov" ]

kib2, note: the web based dictionary is older and less updated than 
the word browser, but it works OK.

kib, to avoid confusion, remember that everything in REBOL is a word. 
The word in itself doesn't have a certain meaning. The words have 
meaning, when used in a context. The same word can mean different 
things in different contexts. And you can redefine everything, even 
things like: + and -

Geomol: something like you and I described would probably be possible 
to do in library , probably not that effective but it should surely 
be possible

When thinking deeper, I'm not even sure, what I just said is completely 
true. haha

Isn't REBOL wonderful!? ;-)

I guess, a number like 1 can't be said to be a word, and it can't 
be redefined. But you can make a dialect, in which 1 means something 
else. So you have words, numbers, blocks, etc. The words can be redefined 
to suit your needs.

kib, you should also read about all the values at some point, appendix 
1 in the Users Guide: http://www.rebol.com/docs/core23/rebolcore-16.html

Geomol: That's really cool; data is code and vice versa, like in 
Lisp ?

I don't know much about Lisp, but I guess, yes.

Crazy example:

>> set '+ :-
>> 5 + 3
== 2

so is there something like quotations in Lisp ? ie something to get 
a word not to be evaluated

yes, "code is data is code" is essential to REBOL.

that's lit-word

Geomol: you answered my question ! It's the ' operator, that's it 
?

yes

>> a: 2
== 2
>> b: a
== 2
>> c: 'a
== a

hehe

wondeful

oh cool... Kib2 our french math professor (I was worried that you 
quit too early Rebol)

Steeve: In fact I've leaved because Carl was not in the mood for 
releasing a public R3 (see my posts on his blog). Then he was kind 
enough to change his mind...

i saw your comments, that's why i was soo worried ;-)

also blocks don't evalueate , thats thy you can make your own >>do-five-times 
[ print "ups" ]<< which is a stupid example :)