Re: [boost] [shared_ptr] dangerous implementation of moveconstructor

From: Joe Gottman (jgottman_at_[hidden])
Date: 2007-04-16 20:07:17

Peter Dimov wrote:
> Joe Gottman wrote:
> 
>>     There are many more ways to reuse an object than assignment and
>> reset.  For instance, I would be extremely disappointed if the
>> following code didn't work:
>>
>> vector<double> foo;
>> vector<double> bar = move(foo);
>> foo.resize(10);
>> for (size_t n = 0; n < 10; ++n) {
>>       foo[n] = n + 7;
>> }
> 
> The code will work under any implementation of the move constructor, IMO. 
> The more interesing question is, given:
> 
>     bar = move(foo);
> 
> would you be extremely disappointed if foo doesn't retain its allocator 
> instance but gets bar's after the move?

    No, but I would expect foo.get_allocator() to return some valid 
allocator and not cause a segmentation fault.  In general, I don't want 
functions that previously were always safe to be unsafe after a move.

Joe Gottman