Hi all,
I updated the http://www.rebolforces.com/~ladislav/contexts.html as well as
contexts.r at the same location to reflect the differences found by Romano.
Thanks again, Romano.
Cheers
L
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Hi Romano,
nice code samples. I can say that you revealed some bugs in the Rebol
interpreter behaviour as well as in my simulator. To obtain accurate results
I would have to modify my simulator as follows:
blank-object: function [
{make a blank object}
set-words [block!]
Hi Ladislav,
blank-object: function [
{make a blank object}
set-words [block!]
] [object] [
set-words: compose [return self (set-words)]
object: do does [
make object! set-words
]
set/any in object 'self ()
Hi Ladislav, looking at your
sim-make-object!: function [
{MAKE OBJECT! simulation}
[throw]
spec [block!]
] [set-words object sw] [
; find all set-words in SPEC
set-words: copy []
parse spec [
any [
copy sw
Hi Romano,
you got me again! My models are unable to demonstrate the behaviour your
code relies on:
Romano
...
not so readable, i must admit (and 'object could be replaced by 'set-words
to
make it more unreadable):
blank-object: func [
{make a blank object from a block of set-words}
Ladislav, I now understand your point, thanks. :)
Anton.
Hi Anton,
a little discussion may be useful sometimes:
Cheers
L
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Hi Ladislav,
cunset in blk: context compose [exit (blk)] 'self
blk
]
/Romano
:-o I would have guessed, that the only way how to do that would be:
blank-object: func [
{make a blank object}
blk [block!]
] [
unset in blk: context compose [return self (blk)] 'self
Hi Romano,
Romano
Hi Ladislav, looking at your
sim-make-object!: function [
{MAKE OBJECT! simulation}
[throw]
spec [block!]
] [set-words object sw] [
; find all set-words in SPEC
set-words: copy []
parse spec [
any [
Hi Ladislav,
No, I think, that my code works. (Test it, please, and let me know if
anything doesn't work as it should).
...
Why do you suggest this form? (I never wrote code looking like that - loop 1
or catch are unusual for me in this case)
For test, try the code at the end. The new
Hi Romano,
thank you,
Romano
Hi Ladislav,
cunset in blk: context compose [exit (blk)] 'self
blk
]
/Romano
:-o I would have guessed, that the only way how to do that would be:
blank-object: func [
{make a blank object}
blk [block!]
] [
unset in blk: context compose
Hi Anton,
a little discussion may be useful sometimes:
Anton
Ladislav, I disagree.
I don't think this is an adequate proof.
(You didn't observe the scan happening,
so it's a theory, not an observation.)
/Anton
You are right. It is a theory supported by observation. In
-
From: Anton [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Tuesday, April 30, 2002 7:12 PM
Subject: [REBOL] Re: local vars in functions
Ladislav, I disagree.
I don't think this is an adequate proof.
(You didn't observe the scan happening,
so it's a theory, not an observation.)
In my
Hi,
Rethinking at my previous message, i must change one thing. At the start of
the block context, the first (set)word is a strange word which i don't
understand well. Could it be a bug?
This is OK:
foo: 0 foo2: 1
make object! [get 'foo2 foo: 2 foo2: 3]
** Script Error: foo2 has no value
**
Hi,
because my example in the first message used the first strange-buggy word
of context, it was wrong, a correct version could be:
a: b: 1
make object! [print value? 'b a: b: ]
false
which confirms that 'b is local and unset.
---
Ciao
Romano
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Hi,
I don't think, that the difference between CONTEXT and FUNC is as clear as
Holger states. First of all, I think, that it is a matter of preferences
(which may differ). To demonstrate, that the difference is really small,
let's have a look at the following code sample:
blk: [change at
Hi,
just a note: you would have to define print func as global too for your
code to work (that is why this isn't a good alternative). I once suggested
another possibility: what if every set-word automatically declared the word
as local, while other word would be local by default (which is usual
Hi Ladislav,
1. I am amazed to see such a long post from you (just kidding).
2. I am testing my new foxmail email reader.
Patrick
Hi,
just a note: you would have to define print func as global too for your
code to work (that is why this isn't a good alternative). I once suggested
another
Hi,
Holger
It is the result of REBOL being an interpreter, not a compiler. A compiler
examines the complete body of a function before generating code, so the
variable declaration can be anywhere. For an interpreter there are only two
options:
1. Make the context of a function static, i.e.
Interesting idea Rishi, but I don't really like it.
I am sure I would go mad trying to distinguish single
or double colons everywhere.
I think it would replace one type of hard-to-detect bug
with another. (ie. accidentally writing only one colon.)
The way rebol is at the moment is explicit and
On 24-Apr-02, Rishi Oswal wrote:
Using the :: shortcut in a global context would be
the same as using a :.
The disadvantage I see is that it adds another thing
to the language.. But consider that now we could stop
using the /local keyword, reduce bugs, and use it
consistently everywhere,
Hi Rishi,
Rishi
One part of REBOL that can feel odd is when i have to
define local variables of a function in the first
block of the function. I find it a bit annoying to
have to add new variables to the list for every little
local variable I use. In addition, I feel it clutters
up the first
Hi, Rishi,
My uninformed $0.02...
(Note that I try to make an alternative suggestion at the
end of my discussion. I'd be interested in feedback on
that idea!)
The main root problem I have with your suggestion is that it
seems to make an assumption about REBOL that I do not believe
to be true
myfunc: func [][
localvar:: $25
myinnerfunc: func [][
innerlocal:: $10
print localvar ; prints $25
]
print innerlocal; error!
]
print localvar ; error!
using the :: for local var will make it more
convienient to create local vars (which i use all the
time over global
Hello Gregg,
GI UNFREEZE context
GI extend context
GI FREEZE context
Actually it would have felt a bit more intuitive for me to actually
specify variables that were global, and not mention variables that are
local specifically. If only because the way I code that would
--- Carl Read wrote:
I like the idea and the syntax, but what happens
with the likes of
this...
a: 10
a:: 20
a: 30
Does that produce an 'a in both the global and local
context? And if
so, does the third expression above change the local
or global value,
or both?
here is another possible brainstorming idea for
int/adv users without changing things for beginners.
REBOL []
globvar1: $1000
globvar2: $
myfunc: func [/global globvar1] [
localvar: $25
print globvar1
print globvar2 ; error
myinnerfunc: func [/global
On Tue, Apr 23, 2002 at 08:08:15PM -0700, Rishi Oswal wrote:
One part of REBOL that can feel odd is when i have to
define local variables of a function in the first
block of the function. I find it a bit annoying to
have to add new variables to the list for every little
local variable I use.
Hi Rishi,
*Syntactically backwards compatible with rebol
I'm relatively new to REBOL (8 months or so now) but I've learned that Carl
and Holger think about these kinds of things very carefully. As Carl has
said, lexical space is very tight in REBOL because of the high number of
native
* Rishi Oswal [EMAIL PROTECTED] [020423 19:18]:
One part of REBOL that can feel odd is when i have to
define local variables of a function in the first
block of the function. I find it a bit annoying to
have to add new variables to the list for every little
local variable I use. In addition,
Hi,
Have you looked at function ?
ie
myfunc: function [arg1 arg2] [local1 local2] [source]
or
myfunc: function [
arg1
arg2
] [
local1
local2
] [
source
]
it pretty much what you want, plus if you use the following
-Original Message-
From: [EMAIL
One part of REBOL that can feel odd is when i have to
define local variables of a function in the first
block of the function. I find it a bit annoying to
have to add new variables to the list for every little
local variable I use. In addition, I feel it clutters
up the first block and
I think the reason for making words global by default
is simply because it is the natural thing for a newbie
to the language or beginner to use. I think this was
the right decision.. fits with the rebol philosophy..
The :: solution, i feel, has the benefit of not
getting in the way of beginners
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