[REBOL] Re: Antwort: Re: Antwort: Switch! (LONG)
From: brett:codeconscious at: 21-Nov-2000 23:02
> You said "Yell", well I´m yelling!
:)
> result-block: make block! (multiply 2 length? index-block)
> could you tell me why you initialized the block in this form?
Only that I believe it pre-allocates memory for the new block to that size.
Everything between ( and ) just calculates how many elements I expect in the
final block. It is purely a performance tweak.
> I´ve noticed
> that you pass references to blocks and words by copying, e.g
> newblock: copy []
> does it have an advantage over
> newblock: make block! 0 ?
It is shorter. :)
And I'm a little nervous about passing in 0 as an argument to the make
function (programmers superstition?).
Other than that it is exactly the same. If I didn't use copy I would end up
changing my code - so all I'm doing is creating a new empty block that is a
copy of an existing empty block.
Brett.
> foreach [char file-list] index-some-data read %. [
> write-my-page char file-list
> ]
> I presume you "read" the directory in "index-some-data" but without the
> colon? I expected something like this
> foreach [char file-list] index-some-data: read %. [
> write-my-page char file-list
> ]
Nope. index-some-data was a function I defined in my post. It takes a block
as an argument. "read %." produces a block as a result. So all I'm doing is
passing the list of files to my function index-some-data which it will then
chew on for a bit. When it finishes it will return a block that the foreach
will chew on for a bit.
> That means I just have to parse the <title> tag contents of all the files
> in a given directory and pass it as "some-pagerefs" items ?
Hmm. Well if you did you would certainly get a page generated but the hrefs
would not be valid. I didn't actually cater for the titles and the
corresponding files - sorry. I'll have a quick look and probably post
something in a little while that does.
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> This is one of the parts that I like best
> "either indexed-item: find index-block first item ["
> I never thought that the left to right evaluation in REBOL could also be
> passed as a expression to "either" or "for"
It gets better. Either and for return values too - the last value in their
blocks.
>> print either [equal? 1 1] ["yep"]["nup"]
yep
