Can an object destroy itself?

问题

I have an object which needs to destroy itself.

Can it be done?

Is the example wrong?

void Pawn::specialMoves(Coordinate const& from, Coordinate const& to, int passant)
{
   /*...*/
    m_board->replace(to, new Queen(m_colour));//replace pawn by queen
}

void Board::replace(Coordinate const &to, Piece* newPiece)
{
    delete tile[to.x()][to.y()];
    tile[to.x()][to.y()] = newPiece;
}

回答1:

Yes, it's legal to call delete this from inside a member function. But there's very rarely a good reason to do so (especially if you're writing idiomatic C++ where most memory-management tasks should be delegated to containers, smart pointers, etc.).

And you need to be very careful:

the suicide object must have been allocated dynamically via new (not new[]).
once an object has committed suicide, it is undefined behaviour for it to do anything that relies on its own existence (it can no longer access its own member variables, call its own virtual functions, etc.).

回答2:

Here's a good sanity check for performing delete this.

回答3:

Yes, it should work. Even delete this; is allowed.

But the code calling specialMoves() could be in for a nasty surprise.

回答4:

Q: Can an object destroy itself?

A: Sure. "delete this" is a popular idiom in COM/ActiveX

As far as your algorithm, I'd suggest:

a "board" object has "tiles". Perhaps just a simple 2-D array.
You start out with n "pieces"
Some controller (perhaps a "game" object), moves a "piece" with respect to a "tile".
Each "tile" has a reference to 0 or 1 "pieces"

I'm not sure I see any reason to create or delete anything on a per-move basis.

IMHO...

回答5:

As long as you don't access member variables or the this pointer after the call to destroy the object, you should be fine. Since it doesn't appear you're doing either of these things, the example should work.

来源：https://stackoverflow.com/questions/9864387/can-an-object-destroy-itself

标签

c++

object

destroy