Super-dee-duper D features

[Andrei Alexandrescu (See Website For Email)]

renoX wrote:
> Andrei Alexandrescu (See Website For Email) a écrit :
>> James Dennett wrote:
>>> C++, of course, has std::for_each(e.begin(), e.end(), do_x);
>>> in its library (though that's weaker than it could be because
>>> of lack of support for convenient anonymous functions/lambdas).
>>>
>>> C++0x is very likely to have for(v: e).  It's implemented
>>> in ConceptGCC already. Java already has essentially that,
>>> as does C#.  This really doesn't set D apart (but at least
>>> D isn't falling behind here).
>>
>> BTW, D might soon have simultaneous iteration that will blow away all 
>> conventional languages:
>>
>> foreach (i ; coll1) (j ; coll2)
>> {
>>   ... use i and j ...
>> }
>> continue foreach (i)
>> {
>>   ... coll2 finished; use i ...
>> }
>> continue foreach (j)
>> {
>>   ... coll1 finished; use j ...
>> }
>>
>> Best languages out there are at best ho-hum when it comes about 
>> iterating through simultaneous streams. Most lose their elegant 
>> iteration statement entirely and come with something that looks like 
>> an old hooker early in the morning.
> 
> At first, I really didn't like the 'continue foreach', then afterwards I 
> got used to it, I wonder if this is really such a requested feature 
> though, what's wrong with the good old 'for' or 'while' for the complex 
> case?

Absolutely nothing's wrong. The same argument, however, could be 
formulated to render foreach redundant. We have for, don't we.

The thing is foreach is terse and elegant and has a functional flavor 
that gives it safety and power that for doesn't have. It's only natural 
to ask oneself why all of these advantages must go away in a blink just 
because you want to iterate two things simultaneously.


Andrei