World: r3wp

Just one comment

You say, you do not know the content of the block you want to insert.

If you keep the reference to the block, you can always insert later 
into the block.

>> outer: append/only  [] internal: []
== [[]]
>> insert internal "test"
== []
>> outer
== [["test"]]

Yes, I'm aware of that REBOL trick. :-) It's because, what I'm parsing 
might be blocks within blocks in a recursive way.

XML is an example of such a structure. If I see a start-tag, I insert 
the beginning of a block in my result, then parse further in the 
document finding content and other start-tags and so on. The best 
way is to produce the output in a seriel manner from beginning to 
end, like I parse the input.

You can use another block as a stack of  blocks references :

- When you meet a new tag, push the current block reference on the 
stack (insert tail) and make current ref to a new block.

- When you meet a close tag, pop the last reference from the stack 
in the current ref  (pick last, and remove back tail)

Just a word of warning -- use the latest betas for any significantly 
nested block structure.

As I found out the hard way recently, the production releases (at 
least under windows) behave erratically when stressed with a few 
hundred nested blocks. Some problem with garbage collection, apparently.

@DideC

Fine suggestion! I use a similar method to stack the names of the 
tags, so I can produce the correct end-tag (like </tag>), when I'm 
at that point in the parsing. But I've found that appending >>to-word 
"["<< and >>to-word "]"<< works very well, so I've solved my problem.

What's up with this?.. 

>> read http://127.0.0.1:83
connecting to: 127.0.0.1
** Script Error: Invalid argument: /
** Where: to-integer
** Near: to integer! :value

(nevermind, it was the script)

stack: If you are interested, I have implemented a stack! object.

Robert what does the stack! object do?

For a stack, I just do:
stack: []
append stack <something>
remove back tail stack

It provides functions for pop, top, push etc. It implements a stack 
datastructure.

stack: []

push: func[ var-block ][ insert/only stack reduce['set var-block 
reduce var-block] ]
pop: func[][ do first stack remove stack ]
a: 1 b: 2 push[a b] a: 11 b: 22 ? a ? b ? stack pop ? a ? b
; cannot push functions :(

I've not needed a stack so far in REBOL.

In other languages, I usually find myself writing a complete thing 
like Robert has mentioed.

The full works in REBOL would look something like:
  stack/create "xxx"     -- create a new stack called "xxx"
  stack/push "xxx" item  -- push item 
  stack/pop "xxx" item   -- pop item
  stack/peek "xxx"       -- return top item without popping it
  stack/length? "xxx"    -- how many items
  stack/clear "xxx"      -- remove all entries

  stack/discard "xxx"    -- remove all entries and delete the stack

  stack/save "xxx" %file -- write it to a file (may not always be possible)
  stack/read "xxx" %file -- reset to contents of the file

  stack/probe "xxx"      -- return a block of all entries (for debugging)


And, as a stack has  a unique name, an application can be using more 
than one at once.

I thinks the following is a bug. Should I submitted to RAMBO?
>> debase {^@^B^C}   
== #{}
>> debase/base {^@^B^C} 64
== #{}

This are invalid base64 strings. It should return NONE! or ERROR! 
I think.

I agree -> rambo

Well, yes it's not a big deal in Rebol but I prefer to use the normal 
common-sense notation for datastructures. Here it is:

stack!: make object! [
		stack: make block! []

		push: func['value /flattend][
			either (type? value) == block!
				[
					either flattend
						[foreach entry value [insert head stack entry]]
						[insert/only head stack value]
				]
				[insert head stack value]
		]

		pop: does [
			either (length? stack) > 0
			[
				value: first stack
				remove stack
				return value
			]
			[return none]
		]

		top: does [
			if not empty? [return first stack]
		]

		empty?: does [
			either (length? stack) == 0 [return true][return false]
		]

		ontop?: func ['value][
			either value == top [return true][return false]
		]

		instack?: func ['value][

   either result: find stack value [return index? result][return none]
		]

		reset: does [
			clear stack
		]

		size: does [
			return length? stack
		]

		print: does [
			probe reduce ["stack:" stack]
		]
	] ; stack

common sense

 is relative though. Bertran Meyer, the creator of Eiffel, offers 
 a powerful argument that I've come to agree with, that of Linnaean 
 Naming Conventions. For example, a stack has Push/Pop methods, a 
 queue may have Enqueue/Dequeue methods, a list Insert/Remove, a collection 
 Add/Delete. You end up with different names for methods that do the 
 same thing. They just behave differently based on the data structure.

So, in a large class library, or even a medium size one, how do you 
find all the different method names, and how do you remember them? 
His answer is that you give the methods the same name. In REBOL, 
that would mean using words like Insert, Remove, First, Last, etc. 
That's how REBOL works with all it's built-in datatypes, and we like 
it for that, so I think it's worth keeping in mind.

Thats what series are about. :) And we can make our own using ports 
:)

about Roberts stack: most of that is inbuild in series, so why wrap/rename 
it?

Thats something Carl blogged about: Idioms http://www.rebol.net/article/0101.html
would be:
push -> insert stack value
pop -> remove stack ; does not return the value. 

top -> stack/1 ; with path, the if empty? stack[return none] is implicit

POP is about the most useful method that isn't built into REBOL. 
It's nice to be able to remove something and have it returned, rather 
than having the series returned.

my push/pop has the advantage that it pushs/pops a group of variables, 
instead of single values. sometimes handy with recursive parsing.

(and 'pop knows which variables where pushed, so just "pop", not 
"pop[a b]")

pop: partly agreed. but i use the top of stack directly, and poping 
really means "no longer needed.
i don't use   push var  change var   pop var
but   push value   use stack/1   pop

Is there someway to have a function stored as a string, and then 
do it, without triggering the actual function name? ie:

N: {o: func [inpu][print join inpu "ing"]}

so that i get.. 

do N "test"
>> testing

do do N "test"

hehe, thanks

So far I've push'ed and pop'ed stacks (blocks) at the bottom, because 
I presure, it's faster that from the top (because of memory allocation). 
But I haven't actually tested it, and if it's true in all cases. 
Does anyone have experience with that?

boo-boo: func [inpu][if error? try inpu [print "error"]]
boo-boo [do do N "test"]

Looking at 'ALTER.. shouldn't there be a similar word that "If a 
value is not found in a series, append it; otherwise, DO NOTHING?

In other words.. i want to check the series to see if the word exists.. 
if not, add it..

Seems this should be an argument for 'ALTER

addWord: func [ser wrd][if not find ser wrd [append ser wrd]]

unioning your test word with your block of words may work

color: [ red blue green]
== [red blue green]

>> color: union color [red]
== [red blue green]
>> color: union color [yellow]
== [red blue green yellow]
>>

stack: Gregg, yes these are true words about using the same name. 
But let's face reality, those data-structure stuff is quite old and 
is learned at university. Most programmers are used to them. And 
from the name of the functions I can implie to the datastructure 
used. Someone not common with Rebol might not "see" that this simulates 
a stack.

You need to know the common sense data-structures anyway. But to 
be honest, the code is quite dated. I use it in MDP to handle the 
parsing state.

anyone know what causes an error 

** user error: system error: tcp

make error! "system error: tcp"

maybe?

no .. not in this instance.

So far I've push'ed and pop'ed stacks (blocks) at the bottom, because 
I presure, it's faster that from the top (because of memory allocation)

 -- Yes. For block! values that is very true. For list! values it 
 isn't. For blocks it's a zillion times faster...well, for small blocks 
 it's faster and for big ones it's a *lot* faster. If you're making 
 a million changes to a 10,000 item block, it's a big difference.

Q: how can I determine the pointer for a struct!  (or variable)  
for passing this pointer  to a external dll ?

or better explained, howto create a pointer. is there something like 
to-pointer ?

if you pass the struct, a pointer is automatically passed. anyway, 
Ladislav has functions to get pointers to memory. I don't have the 
link at hand though...

you need a pointer to Ladislav's URL struct!    ;-)

took a while to find this ... http://www.fm.vslib.cz/~ladislav/rebol/

not sure that Gab's reference is there, but tons of goodies there...wow!