Re: [boost] what happened to allocators in boost?

From: E. Gladyshev (egladysh_at_[hidden])
Date: 2003-08-06 01:54:46

--- Douglas Gregor <gregod_at_[hidden]> wrote:

> The allocator design focused on the benefits one
> could get from specialized
> allocators for containers, e.g., data structures
> that may allocate large
> chunks of memory that are expected to be used
> together. They don't really
> give us much for components like shared_ptr that
> allocate one thing 

I agree but there is a problem with classes that use
STL and boost components. Here is an example:

template < typename T, typename A = std::allocator<T>
>
class node
{
public:
   shared_ptr< T > m_data;
   std::list<T, A> m_children;
};

When the user writes 
node< MyType, myallocator<MyType> > node;
she will rightfully expect that all memory allocations
of type MyType will use the supplied allocator but
shared_ptr doesn't support it.

The fundamental problem here is that I don't see a
consistent (from the allocation standpoint) way to use
boost and STL components in one class.

>(and
> note that shared_ptr does not allocate the pointer
> it stores, although it
> does allocate a reference count).

How does the reference count get allocated? Do I have
any control over it except overloading the global
new/delete operators?  I am writing a module that
needs to use a custom heap for some of my class
instances. The class has a shared_ptr. I guess that I
cannot use shared_ptr there?

Eugene

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