Re: [boost] auto_vector - vector with auto_ptr semantics

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2002-02-05 11:57:17

On Tuesday, February 5, 2002, at 11:38  AM, Peter Dimov wrote:

> And let's not forget the 'other' move, that moves an object into
> uninitialized memory (move1 and swap both require two objects to operate
> on.) std::vector needs this while reallocating.

Yup!  A minimum of 2 types of move are absolutely necessary:

1.  Move construct.
2.  Move assign.

One could argue that 2 more moves are useful:

3.  Move construct, destructing the source.
4.  Move assign, destructing the source.

However 3 and 4 are very easily built on 1 and 2 by just calling the 
destructor on the source after the move.

This again is just like copy:

1.  Copy constructor.
2.  Assignment operator.

And destruction of the source is a separate and optional additional step.

As Peter says, without move construct, move semantics will not be 
valuable to vector (or deque, or any other array-like container).

-Howard