• Sean Kelly <sean f4.ca> Aug 03 2004
• Juanjo =?ISO-8859-15?Q?=C1lvarez?= <juanjuxNO SPAMyahoo.es> Aug 03 2004
• "Matthew" <admin stlsoft.dot.dot.dot.dot.org> Aug 03 2004

I've been kicking around how to "D-ify" the STL algorithms and ran into a snag:
foreach can only iterate across one range at a time while some of the STL
algorithms want to iterate across two simultaneously.  I'm thinking of things
like lexicographical_compare and such.  On the surface this seems like a strong
argument for iterators, but I'm wondering if there might be a more D-like way to
handle these.  Any suggestions?


Sean

Sean Kelly wrote:

  Any suggestions?


Yes, extend the foreach syntax in the natural way (for D 2.0 of course):

int compare(char[] string1, char[] string2) 
{
        foreach(char c1, int idx : char c2; string1 : string2)
        {
                if (c1 != c2)return idx;
        }
        return -1;
}

or:

foreach(char c1, int idx; string1 : char c2; string2)
{
}

Maybe the ':' is not the best option here, just using some random char to
express the idea. 

Of course this would not be limited to two containers :) One problem you can
have is: What if string1 is longer than string2? What value do you assign
to c2 once it is over the limit?

"Sean Kelly" <sean f4.ca> wrote in message
news:ceoq1l$1hov$1 digitaldaemon.com...
 I've been kicking around how to "D-ify" the STL algorithms and ran into a snag:
 foreach can only iterate across one range at a time while some of the STL
 algorithms want to iterate across two simultaneously.  I'm thinking of things
 like lexicographical_compare and such.  On the surface this seems like a strong
 argument for iterators, but I'm wondering if there might be a more D-like way
to
 handle these.  Any suggestions?


Glad to see you're running into the same thoughts I'd had on that one.

I'm currently wearing two hats on this one. On the one hand, I tend to be in
the Walter camp, in so far as I think D
generics will be different from C++ generics, and we should not worry too much
about that. I must concede that I very
rarely use STL algorithms other than copy(), find(), for_each() and
accumulate().

On the other, I believe that DTL can probably support such things - although it
may have to wait for D 1.0+ language
features - and therefore it _should_ support them.

For my part, I'm putting iterator-based stuff fourth on my Enumeration To-Do
list, behind foreach, interfaces and ranges
(composable foreach). That way, there'll be plenty of scope for finding out if
there is a D way, and I should also be
able to piggy-back on all you smart folks that're trying to do the STL way. <g>


Having said all that, however, I find it incredibly irritating not to be able
to conduct two concurrent enumerations
with the same construct. This should be fixed, somehow.