World: r3wp

From RT Q&A:

Q: While reviewing the action! functions, I noticed the path action. 
The doc comment says "Path selection.". The parameters aren't typed. 
Does anyone know what this action does, and how to use it? Or whether 
it can be or should be called directly at all?


A: the PATH action is what the interpreter uses to evaluate VALUE/selector 
expressions for each datatype. It is an internal action and has no 
external purpose in programs. These kinds of words often appear as 
a sort of "side-effect" from how REBOL is structured.  Datatypes 
are implemented as a sort of object class, where the interpreter 
"sends messages" to the class to evaluate expressions. The PATH action 
is a message that tells the datatype to perform a pick-like or poke-like 
internal function.

Some other discussion:

http://www.rebol.org/cgi-bin/cgiwrap/rebol/aga-display-posts.r?post=r3wp152x1804

http://www.rebol.org/cgi-bin/cgiwrap/rebol/aga-display-posts.r?post=r3wp157x7205

Thanks!

s: "Hi engkau. Mengapa kaulari? Topikau ada di sini dan jaskau ada 
di sana."


In string s above, is there an easy way to replace (with "engkau" 
all instances of "kau" that are not preceeded by  " " (a space) or 
immediately followed by a letter?

In other words, I only want "kau" to be replace with "engkau" when 
"kau" is preceeded by a letter and followed by a space or puncuation 
mark.

Do you want "engkau" to become "engengkau"?

One solution:


s: "Hi engkau. Mengapa kaulari? Topikau ada di sini dan jaskau ada 
di sana."
p: s

while [not none? p: find p "kau"] [either all [p/-1 <> " " find " 
,." p/4] [insert p "eng" p: skip p 6] [p: skip p 3]]

If you don't want "engkau" to become "engengkau", you can use:


while [not none? p: find p "kau"] [either all ["engkau" <> copy/part 
skip p -3 6 p/-1 <> " " find " ,." p/4] [insert p "eng" p: skip p 
6] [p: skip p 3]]

Geomol, thanks!  I'll do some testing and get back with you in a 
few hours.

I have to get some sleep first. :>)

Geomol, perfect! and simple. Many, many thanks! You have saved me 
a lot of time.

:-) I'm glad to help!

Is there a way to detect if a script is run from >> do %script.r 
 versus  $ rebol script.r  ??
I'd like to  either from-console [halt] [quit]

Can't you check on some of the values in system/script ? Maybe system/script/header 
or system/script/args ?

I was playing with those...but you tweaked a memory.  There was a 
weirdness in the DevCon presentation...it was system/options/script. 
 Thanks John.

Much nicer error abends now.

Perhaps system/console/history.

parent of system/script. each 'do adds a header there while the sub-script. 
none? system/script/parrent/parrent IIRC.

..while the sub-script  runs..
try probing system/script from the subscript to figure it out.

I think it comes down to  system/options/script  This seems to only 
be set (at least in GNU/Linux land) when the shell $ rebol script.r 
is used to kick start.  I'm pretty sure I can use this for a reasonable 
bail test.   Regardless of how many do levels down,  system/options/script 
 is the original shell start script name (or none if do'ed)  This 
is reasonable right?  If the user starts from the shell, bail to 
the shell, starts from the console, bail to the console.

i thought you want to check if the do is from another script. you 
want from the console. then you are right.

Thanks Volker, your advice will likely come in handy in the not too 
distant future.  :)

Given a block with one element:
>> blk: [1]
== [1]
I move the blk pointer forward one position:
>> blk: next blk
== []
I then append one element:
>> append blk 1
== [1 1]

and the head of blk is shown, which is the behaviour of append. The 
address of blk is the same:
>> blk
== [1]
I now clear the whole block:
>> clear head blk
== []
and append yet another element to the now empty block:
>> append blk 1
== [1]
But blk now points to the tail of the block!
>> blk
== []

Shouldn't I see the element at the position of blk? I mean, blk should 
now point to the head of the block, right? I couldn't find this in 
RAMBO.

Funny thing is, that if I append yet another element:
>> append blk 2
== [1 2]
the blk pointer now point at element 2:
>> blk
== [2]

So blk had the position 2 all the time, even when the block was empty!?

How does R3 behave in this regard?

tried all steps in r3 and looks exactly same

clear head blk
 doesn't reset 'blk to the head of the series. If you do:

blk: head blk
clear blk

you should get what you expect.

or "blk: clear head blk"

Documentation question again.  Are rebols better described as "programmers" 
or "script writers"?  Target audience; new users (of the rebol.org 
script repository in particular)  And I'll take other suggestions.

Take a look at Gabriele's email signature......

Gabriele Santilli
Rebol Programmer

Thanks Peter

Is it the language, that specify, what you are? With REBOL I think, 
it's possible to be a script writer, a programmer, a developer, a 
designer, an inventor, a tester, etc.. Doesn't it depends on the 
task or job situation, where you use REBOL?

Like there are many different jobs, where you need good english (language) 
capabilities.

I normally call myself a system developer or just developer, because 
I do many different jobs with REBOL, and "developer" is a more generel 
term.

This was in the context of explaining %inhide.r from the rebol.org 
library.  I used programmer.  As in This script helps ensure that 
REBOL programmers know how to hide password input.  It was aimed 
at rebols just starting out.  I usually use rebol to mean  REBOL 
coder but only when I'm chatting to those in the know.  I've tried 
but I can't get my head around the REBOLer expression.  :)

I guess, the confusion come from back, when the term "script writer" 
popped up first, in the '70 or earlier. Script writers were the ones, 
who wrote scripts (e.g. shell scripts), which were typically small 
pieces of code to be run in the shell on large computers (mainframes). 
Those scripts did operating system maintenance and called programs. 
Programs were written in languages as C, COBOL, etc.. So you had 
a clear distinguish between a script writer and a programmer. What 
we do today with REBOL is more often the programmers job (I think), 
even if it's called a script language.

John;  As part of the cool kids hacker culture, you can't call yourself 
elite, but you're L33t.   Or in REBOL speak; guru.   Another name 
that you can't really call yourself, without someone else tagging 
you first.  So there you go, your tagged.   Then again, maybe I'm 
not worthy...I do have my sights set on attaining Bogus status someday. 
 :)

Yep agree.  It's a blurred line now-a-days.  While I was watching 
a group of C++ programmers p#$$ away some 30 million dollars my poor 
little Tcl/Tk prototype just made them mad.  "Not engineered if it's 
scripted!!!"  :)  Oh well, the original Forth system is still in 
production and corporate will try to replace it with a engineered 
solution...usually started with CASE tool cloud diagrams.

What is hidden in the term "engineered"? What do they mean, when 
they say "it's not engineered" or "need an engineered solution"?

geomol, probably a different word in this context for "not invented 
here"

Umm, I think it means they don't get a chance to overthink the problem. 
 Now to be honest, large projects do need a good work breakdown and 
management back end, but the coding usually ends up far too complicated 
to ever get off the ground (in my somewhat limited experience - I 
only watched them fail 5 times so far).  And polyFORTH keeps chugging 
along... and again in a little defense of corporate...they have very 
few L33t's that can handle poly.

I think, you're ok with in general calling the authors of REBOL programs/scripts 
for "REBOL programmers" or "REBOL developers". In most cases it's 
more correct than the term "script writer", as I see it.

Fair enough.  I'll avoid the expression in the library docs.

Ok, next one.  I'm thinking about quit/halt.  If a script is started 
from the console with do,  it should halt to the console right?  
If started from an icon click or a shell command it should quit? 
 Or do people mind just restarting up another REBOL console when 
an app quits on them?  Or other way round, an app started with an 
icon click should never halt, correct?

Started from console, and it should just halt. I get this wrong sometimes 
myself. It could be good to have an equal way of doing this, so please 
tell me, when you find a good way! Standards! (It should also work 
equally on all version of REBOL on all platforms.)

I'm using  system/options/script  - it is only set if a script is 
started up along with REBOL.  I was thinking of posting a   cease 
 idiom.   It is kind of a pain to do a script that quits, but on 
the other hand, I don't think that in the general case, a script 
started from an icon should ever halt, so quit seems to be a better 
'default'.

Inconvenience to coders doing console work but safer for users running 
scripts.

Would it work, if scripts always use QUIT, and then when in a console, 
we redefine QUIT like:
>> quit: :halt

I like that idea.  %user.r could check if system/options/script is 
set (maybe).

HALT is then only used in situations, where scripts should return 
to the console, nomatter if it was started from the console or the 
desktop.

I'd buy into that.  Now can someone wield a big enough stick? :)

what is the official definition of an action! ? I keep forgetting 
the difference between actions and natives.