[boost] Re: looping construct

From: Daniel Wallin (dalwan01_at_[hidden])
Date: 2004-04-22 05:02:11

Eric Niebler wrote:
> 
> Daniel Wallin wrote:
> 
>>
>>   xxx::for_each(cont, _1 += 2);
>>
>> IMO C++ isn't missing a loop construct, it's missing a lambda construct.
>>
> 
> IMO, C++ is missing a foreach construct *and* a lambda construct. :-) 
> When the loop body is non-trivial, writing it as a lambda would make the 
> code hard to follow. 

Why? I don't see why there should be much of a difference.

   foreach (x, v)
   {
       ...
   }

  vs

   for_each(v,
     lambda(x) {     // or whatever a lambda syntax would look like
       ...
     });

> I shudder at the thought of a lambda that takes up 
> more than a few lines. A foreach construct would make it easier to read, 
> in that case.

But then again, if we had a type inference mechanism and a range library
the for-loop is easy enough:

   for (auto r = range(v); r; ++r)
   {
   }

I would agree that there would be need for a simpler loop head if we had
to write every trivial loop on our own, but we have standard algorithms.

That said; there might be need for your macro right now, since we don't
have auto or lambda yet. :)

-- 
Daniel Wallin