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[REBOL] Re: Newbie Q: Cropping text

From: chalz:earthlink at: 9-Jul-2002 1:35

First off, my thanks to everyone demonstrating The Way Things Work. I don't get to work in REBOL all that much anymore, so what knowledge I had of it has dwindled, and I find myself looking at older code of my own and thinking, "Why did I do that? It works, but *how* does it work?"
> char-sequence: next [a b c d e] > > This line has three values - a set-word!, a word! and a block!. When this > line is evaluated, again a block! series of values will be created, this > time of five words (a, b, c, d, e). The block! will be at its head (head? > returns true). Then NEXT is evaluated and it takes the block as input. NEXT > returns a different block! value - that is the new block! has a different > index to the original but retains a reference to the same sequence of > elements. Finally in the evaluation, char-sequence is set to refer to this > new block! and if you perform INDEX? on char-sequence afterwards, you will > get the value 2 returned. If you performed FIRST HEAD char-sequence you > would get the value 'a returned.
Whoah. That.... damn. That's just screwed up. So if I POKE a new value into the original sequence, the char-seq gets changed as well. Wow. Time to make prodigious use of COPY, it looks like. *whistles*
> So now this next expression of six values > a: next b: next c: next sequence: [a b c] <snip> > Now if you try printing A you will get an error message. This is because A's > index is past the tail of the series. But A can still be used try printing > HEAD A. So in this last example I have made four seperate references to the > same underlying data series and each of these is referred to by a different > word (A, B, C and Sequence).
AAAAAIIIIIEEEE!!!!! *gun shot*
> > Thanks for your help, Brett. > > My pleasure. I hope the descriptions above are useful and not uselessly > wordy!
Heh. No, not too wordy. However, I am now frightened of REBOL ;) CarlS is certainly a madman ;) --Charles