Re: Elegant code

Jonah Thomas <jethomas5@[EMAIL PROTECTED]
> wrote:
>
>: GOOD-STRING1 ( S: ca len xt -- ca len' )
>    >R
>    2DUP BEGIN 
>      DUP 0 > WHILE   
>        OVER R@[EMAIL PROTECTED]
 EXECUTE WHILE
>          1 /STRING
>      REPEAT
>    THEN
>    NIP - RDROP ; 
>    
> This works adequately but it's clumsy. A complicated loop and a return
> stack item.

I don't see anything wrong with using a return stack item...actually I
rather like the return stack for things like this.  I find it easier to
remember that there is one thing on the return stack, and what it is,
than remembering the order of the three things on the data stack.

And you have two loop-ending conditions, so it's bound to be at least
slightly complicated.  And this is a low-level word, so IMO a bit of
complexity is acceptable...


I found this in one of my programs:

\ For both of the following words, XT should be ( char -- flag )

: SKIP-WHILE ( addr u xt -- addr' u' )
    >R BEGIN DUP WHILE
        OVER C@[EMAIL PROTECTED]
 R@[EMAIL PROTECTED]
 EXECUTE WHILE 1 /STRING
    REPEAT THEN R> DROP ;

: SPLIT-WITH ( addr u xt -- addr' u' addr u2 )
    >R 2DUP R> SKIP-WHILE  2TUCK NIP - ;


> I can make it look nicer.
>
>: CHECK-STRING5 ( xt ca len -- xt ca' len' )
>    3DUP 0 > IF
>      SWAP EXECUTE IF 1 /STRING RECURSE THEN
>    THEN ;

I like that...except you need a 3DROP after the final THEN.

> 3DUP is not really simpler than 3PICK . It's easier for me to see what's
> going on, but the obvious way to implement 3DUP in high-level standard
> Forth is : 3DUP 2PICK 2PICK 2PICK ;

I think 3DUP is definitely simpler than 3 PICK, but then I don't really
care about the implementation; just whether I can read the code.

--Josh