[boost] Re: [Formal review] Collection Traits library

From: Thorsten Ottosen (nesotto_at_[hidden])
Date: 2004-05-08 07:07:30

| > Pavol uses it havily in his string library. The "dangerous" thing would be not to put
| > computation of the end-iterator out-side the loop, eg.
| >
| > for( iterator_type_of<T>::type i = begin( c ); i != end( c ); ... )
| >                                                                   ^^^^^^^^^^  ^
| > is not good. But one wouldn't do that anyway. And if one did it, what are the chances of
| > the argument being a char*?
| 
| Too many chances are being taken here, IMO. 

the more chances that are taken, the less the likelihood of it all happening.

| It doesn't feel right.
| STL's end is guaranteed O(1) and I'm really concerned about anything
| that violates that expectation.

ok. I have forgotte why Pavol want to support char* at all. I mean, programming with manual
insertion of null is really error-prone. If char* is considered a range, one might even say

std::string s;
my_algo( s.buffer() ); // oops, no terminating null!
 
| Maybe the string algorithm library ought to use a different name for
| this; for example:
| 
|   sentinel_type_of<T>::type f = finish( c );
|   for (iterator_type_of<T>::type i = begin( c ); i != f; ++i)
|       ...

A predicate like yours above is better in that context. I think Eric does that in for each.   

|   template <class T>
|   typename iterator_type_of<const T>::type finish(T const& x)
|   { return x.end(); }
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
typename const_iterator_of<T>::type 

br

Thorsten