Higher level built-in strings

[Michel Fortin]

On 2010-07-20 00:31:34 -0400, Walter Bright <newshound2 at digitalmars.com> said:

> Steven Schveighoffer wrote:
>> I agree here.  Anything that uses indexing to perform a linear 
>> operation is bound for the scrap heap.  But what about this:
>> 
>> foreach(c; str)
>> 
>> which types c as char (or immutable char), not dchar.
> 
> Probably too late to change that one.

Sad. That's one of the first things I tried when I first learned D and 
the result did surprise me. I expected foreach to iterate on characters 
(code points), not code units. Then I saw I could add 'dchar' to get 
that behaviour and found that to be not too bad.

The big problem here is that ranges and foreach behave differently. A 
range that doesn't work with foreach isn't a good range. That's even 
worse when that range is at the core of the language because it'll look 
bad on both ranges and the language.

As it stands now, when doing generic programming we'd have to write 
foreach like this so it works the same with foreach as it does with the 
range APIs, just in case the range is a string:

	foreach (ElementType!(typeof(range)) c; range) {}

Something needs to change so the above always work the same as not 
specifying the type! Either foreach should be adapted or ranges should 
let go the idea of iterating on code points for the default string type.

As for the "too late to change" stance, I'm not sure. It'll certainly 
be to late to change in a year, but right now D2 is still pretty new. 
What makes you say it's too late?

-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/