Reputation: 462

Can an object destroy itself?

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;
}

Upvotes: 21

Answers (5)

John Calsbeek

Reputation: 36497

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

Upvotes: 12

Oliver Charlesworth

Reputation: 272517

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.).

Upvotes: 38

paulsm4

Reputation: 121669

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...

Upvotes: 1

tmpearce

Reputation: 12693

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.

Upvotes: 0

Henk Holterman

Reputation: 273274

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

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

Upvotes: 2

Can an object destroy itself?

Answers (5)

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