Re: [boost] [review] Review of Unordered library begins today December 7

From: David Abrahams (dave_at_[hidden])
Date: 2007-12-12 07:57:45

on Tue Dec 11 2007, Thorsten Ottosen <thorsten.ottosen-AT-dezide.com> wrote:

> David Abrahams skrev:
>> on Sun Dec 09 2007, Thorsten Ottosen <thorsten.ottosen-AT-dezide.com> wrote:
>
>>> says that erase() does not throw for ordered containers (which is 
>>> correct). Anyway, this means any argument used to assume that predicate 
>>> evaluation is a no-throw should be the same for unordered containers.
>> 
>> No, the ordered containers don't do any predicate evaluation in
>> erase().
>
> How can you implement
>
>    std::set<T>::erase( const T& )
>
> then, if you are not going to find the equivalent elements by evaluating 
> Pred(x,y)?

Sorry, I forgot about that one; I was just thinking of
erase(iterator1, iterator2) and erase(iterator)

>>> Why does erase( const_iterator ) (and range version), not provide the
>>> no-throw guarantee?
>> 
>> Why should it?  Vector/deque erase don't.
>
> Because it is a node based container.

Yeah, but it might rehash.

>>> Does erase give the strong guarantee otherwise?
>>>
>>> Since erase(const Key&) for ordered containers cannot throw, so I guess 
>>> it is implicitly  required that Pred(x,y) must not throw? 
>> 
>> Nope, see above.
>
> Still don't get it.

Hmm, I need to go back and check the draft standard.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com