Re: [Boost-Users] Class destructor invocation - possible by hand?

From: George A. Heintzelman (georgeh_at_[hidden])
Date: 2002-01-17 12:12:05

> > Also, I would recommend that you either reconsider
> > having the constant member variable, or use a
> > vector<>.
> 
> Using a vector<T> won't work in this case, because the STL uses
> T::operator = in order to copy vector contents into new locations during
> memory reallocation. And there's no logical way to implement operator =
> when a const data member is present, which is the cause of this
> conversation.
> I could use std::list, since it doesn't do reallocation, but clients
> using this class in containers will most likely need random access
> iterators.
> 
> Any other ideas?

Easy option: Use a vector<shared_ptr<T> >. This will give you basically 
the behavior you want, with the ability to initialize the elements 
directly. The drawback is that the data will be dynamically allocated.

Harder option: Write a new container class which doesn't supply dynamic 
allocation, and thus changing capacity (templatize it on the maximum 
capacity, and you can store the data on the stack) but does supply 
resizing up to that maximum capacity, keeping unused elements 
unintialized, calling the destructors appropriately, initializing new 
elements with the copy constructor. Be aware that you won't be able to 
sort the container, since the elements lack operator=, or use insert or 
erase (pop_back and push_back only will work). You should supply this 
insert and erase functionality anyway, in case someone uses your 
container with a type supplying operator=.

Submit your new class to boost for others to use.

George Heintzelman
georgeh_at_[hidden]