On Mon, Apr 28, 2008 at 02:37:03PM +0100, Donal K. Fellows wrote:
>  Kevin Kenny wrote:
>  > Uhm, Donal, excuse me?  This is a simple forward iteration. Keep an
>  > index into the string rep - as opposed to the 'string' internal rep.
>  > (That one never shimmers.)  On each trip through the loop, decode
>  > one UTF-8 character and advance the index around it.  There's no
>  > real slowdown because you don't need to get into quadratic behaviour
>  > counting the UTF-8 characters (the way a naively coded [string index]
>  > loop at Tcl level would).
>  > 
>  > If you want to cache single character strings (at least for
>  > ISO8849 characters), go for it.  But I suspect that in most uses
>  > of this, the single characters would be short-lived.
>  
>  Bah, this whole discussion is getting out of hand (and I'm highly
>  irritable today because I'm teaching). For the business of [string
>  foreach], I'd be perfectly happy to see an implementation as you
>  describe it. Since it's iterating by single characters, the benefit of
>  buffer sharing would be slight. Whether or not to cache character-objs
>  would be a question to decide at a later date.

Is it possible we're talking past each other?  I get the feeling you are
seeing a more complicated picture than I am.  I was thinking something
like what Kevin wrote.  The only thing that is complicated is that 
you have the source buffer having an extra reference count for the
duration of the loop.  The chars themselves are extracted one at a
time and stuck into another tcl obj that has no unusual ref counting.
So this approach should be, for long strings, much nicer than
using split.

I'm wondering if you thought I was asking for the reference count 
jiggering to be on both the char and the string so the char shared
the strings refcount or something.  If so, no, that's too wacky for
me.
-- 
---
Larry McVoy                lm at bitmover.com           http://www.bitkeeper.com

-------------------------------------------------------------------------
This SF.net email is sponsored by the 2008 JavaOne(SM) Conference 
Don't miss this year's exciting event. There's still time to save $100. 
Use priority code J8TL2D2. 
http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone
_______________________________________________
Tcl-Core mailing list
Tcl-Core@[...].net
https://lists.sourceforge.net/lists/listinfo/tcl-core