Re: [boost] auto_vector - vector with auto_ptr semantics

From: Mark Rodgers (mark.rodgers_at_[hidden])
Date: 2002-02-03 15:38:49

From: "Rainer Deyke" <root_at_[hidden]>
> It sounds like your 'auto_vector' avoids some of the problems of a
> container of auto_ptrs by conceptually being a container of vanilla
> pointers.  Unfortunately this has its own set of problems.  Consider:
> 
>   auto_vector<Cat> cats;
>   cats.push_back(new Cat);
>   cats[0] = new Cat; // Error: memory leak

With my current version, yes this is unfortunately true.  I know 
enough not to do that, and so it has never been a problem for me.
I regard auto_vector as being convenient and not full proof.  

If more safety is required, I guess we could look at making 
operator[], front, and back return values rather than references.
But it would still cause a leak if you did a 

  *cats.begin() = new Cat;

We could then make all iterators const, but that would stop us
sorting the vector.  Then I guess we could add a sort member 
function.

Or I guess we could go the whole hog and return some sort of 
proxy that deleted the current pointer on assignment.

But I don't know if the added safety of either is worth the 
trouble.  What do others think?  Keep it simple or make it safe?

Mark