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RobertS
9-Sep-2007
[820]
I wil be sure to cover  get/any  and  set/any 
thanks
RobertS
12-Sep-2007
[821x10]
; using a context there is no problem traversing a path into nested 
blocks. But there is using nexted blocks alone.  Here is my first 
answer to this...
>> t1: [a "one" b "two" c "three"]
== [a "one" b "two" c "three"]
>> t2: [f t1]
== [f t1]
>> t1/b
== "two"
>> t2/f
== t1
>> t2/f/b
** Script Error: Cannot use path on word! value
** Where: halt-view
** Near: t2/f/b
>> pword: func [path 'word /local blk] [
[    return to-path reduce[path :word]]
>> do pword t2/f c
== "three"

; pword is my first pass at a function to traverse nested blocks 
which are not in an object; the alternative appears to be
blk:  get t2/f
aPathDeeper: make path! [ blk c ]
; anyone know anoth path to take?
; the local was a hold-over from an earlier pass at doing this


pword: func [ { navigate one deeper into nested blocks using a path} 
path 'word { must be a valid path refinement} ] [
  return to-path reduce[path :word]]
; simple nested blocks were not the issue
>> t1: [a "one" b "two" c "three" x [f "for"]]
== [a "one" b "two" c "three" x [f "for"]]
>> t1/x
== [f "for"]
>> t1/x/f
== "for"
; I only have the issue if I build t2 to hold some functor and a 
word bound to a block rather than the block, i.e., not
>> t1: [a "one" b "two" c "three" x [f "for"]]
== [a "one" b "two" c "three" x [f "for"]]
>> t2: reduce['functor t1]
== [functor [a "one" b "two" c "three" x [f "for"]]]
>> t2/functor/c
== "three"
t2/functor/x/f  ; also OK of course
; this issue persists 
>> t2: [functor t1]
== [functor t1]
>> p3: to-path reduce[ t2/functor 'x]
== t1/x
>> do p3
== [f "for"]
>> p3: to-path reduce[ t2/functor 'x/f]
== t1/x/f
>> do p3
** Script Error: Invalid path value: x/f
** Where: halt-view
** Near: t1/x/f
; there seems to be no way to "append'" to a path ??
>> p4: to-lit-path [t1 x/f]
== 't1/x/f
>> do p4
** Script Error: Invalid path value: x/f
** Where: halt-view
** Near: t1/x/f
>> t1/x/f
== "for"
; this works
>> p4: to-lit-path 't1/x/f
== 't1/x/f
>> do p4
== "for"

; but it is no help if t am trying to pass in the path the I wish 
to "extend" deeper
>> p4: to-path "t1/x/f"
== t1/x/f
>> do p4
** Script Error: Invalid path value: t1/x/f
** Where: halt-view
** Near: t1/x/f
>> type? p4
== path!
>> get first p4

** Script Error: get expected word argument of type: any-word object 
none
** Where: halt-view
** Near: get first p4

; using get first or get second or get last usually is handy diagnosing 
what is reported as a path but in fact fails as a path
>> p4: to-path 't1/x/f
== t1/x/f
>> get first p4
== [a "one" b "two" c "three" x [f "for"]]
Chris
13-Sep-2007
[831x3]
; If I'm understanding this correctly, you are trying to resolve 
a single path to a value in nested blocks (I'll take the liberty 
of reimaging the example):

path: 'language/en/one
language: [en english]
english: [one "one" two "two"]

resolve path ; == "one"
; I'd look at this in two ways -- a) set up the blocks so the path 
works with 'do:

language: reduce ['en english]
resolve: :do

resolve path ; == "one"
; or b) step through the path and resolve each value in turn:

resolve: func [:path [path!] /local wd val][
    wd: first path: copy path remove path val: get wd
    while [all [block? val not tail? path]]
        wd: first path remove path
        val: val/:wd
        if word? val [val: get val]
    ]
    val
]
RobertS
13-Sep-2007
[834]
I am trying to compare what I can do in Rebol to what I can do in 
another language with functors

What hamstrings me is that a path cannot be extended unless the blocks 
are literally nested or in an object

I am hoping some one will da ythat in R3 path! is more like a series!
path: this/thing
path: append path 'what
rez: path
Chris
13-Sep-2007
[835x2]
(sorry, missed an opening bracket in 'while)
path: 'this/thing
append path 'what
probe path
probe to-block path
RobertS
13-Sep-2007
[837x3]
sorry what is a bad choice
make that 'whatever
bind to two valid paths
compose with one word nested in a block
you can append all you want
type? is path
and the path will not be valid
my little pword func was the shortest thing I could build
Chris
13-Sep-2007
[840x2]
path: join 'language/en 'one
probe resolve path
path: join 'language/en 'two
probe resolve path
The path is not valid, so long as you are trying to resolve it with 
'do.
RobertS
13-Sep-2007
[842x4]
why should that be so?
the path is just word1/word2 and then is just word1/word/word3

Only word1 ever binds to a value
word1/word2/word3 ; guy can't even type ...
The path! that my 'pword func returns responds as expected to 'do
Chris
13-Sep-2007
[846]
Iin your example (again, if I understand correctly), 'do (or default 
behaviour) resolves each stage in the path.  So, with a given path 
-- t2/f/b -- it'll go t2/f == 't1-- but this is just a word, not 
the value associated with the word.

It's equivalent to this:
val: 't1
val/b
RobertS
13-Sep-2007
[847]
But is any valid deep path only the forst word has to have  a value 
associated with it.
  e.g. 
     block/tag1/tag2/tag3
Chris
13-Sep-2007
[848]
Only if you're evaluating with 'do.
RobertS
13-Sep-2007
[849]
Even if I am doing
   result: constructedPath
Chris
13-Sep-2007
[850]
That's sort of the same as evaluating with 'do.
RobertS
13-Sep-2007
[851]
What should the behavior of 'join and 'append' and 'insert be when 
passed a path and a word?
Chris
13-Sep-2007
[852]
What I'm getting at is there are limitations in the default handling 
of paths.  But paths are series and you can evaluate them however 
you want to.
RobertS
13-Sep-2007
[853x2]
Yes, get first path is a godsend
Here is what Carl has said:

Of course, not to discourage anyone, but we're going to be careful 
and choosy about what becomes part of R3. We've got our standards. 
We still value small, fast, and smart. REBOL is about getting great 
advantage and leverage from a well-designed tool, not about becoming 
yet another bloated and hard-to-manage computer language.
Chris
13-Sep-2007
[855]
join foo/bar 'ton -- will try and evaluate foo/bar then append 'ton
join 'foo/bar 'ton -- will give you 'foo/bar/ton
RobertS
13-Sep-2007
[856]
That is great but also of no help if a word is holding the path
   'foo/bar
I was hoping the solution was in
   to-lit-word
Chris
13-Sep-2007
[857]
path: 'foo/bar
join path 'ton ; ??
RobertS
13-Sep-2007
[858]
fails with 
  ** Script Error: Cannot use path on word! value
Chris
13-Sep-2007
[859]
Hmm, works here.
RobertS
13-Sep-2007
[860x2]
to-path reduce[path 'word]   ; works OK but what a klunk
Only if the blocks are literaly embedded.
Could you try with the example
  t1
  t2
Chris
13-Sep-2007
[862]
join to-path 't2 't1
RobertS
13-Sep-2007
[863x3]
no, in the example that I posted above :-)
>> t1: [a "one" b "two" c "three"]

>> t2: [f t1]
'f has no value so it is just like a functor
I am not askeing to be able to just use
   t2/f/a
with no further ado
I must build the path
   newPath: to-path reduce [ t2/f  'a]

is a pain ( and only because of how to-path is implemented;  to-lit-path 
is no more help as far as I can see at this hour
Chris
13-Sep-2007
[866x2]
I'm not sure why -- newPath: join 't2/f 'a -- doesn't work...
Hold on, -- join to-path t2/f 'a --??
RobertS
13-Sep-2007
[868x2]
That just caused Rebol 2.6.3 to blow away
I did not send teh missuve to Microsoft that I was proffered
the missive