is selfdestruct a good practice?

Question

A contract after selfdestruct cannot manage transactions, and as such any ether sent to it is lost. Wouldn't be better to switch to a contract defined state "dismissed" and reject any ether sent by mistake when in such a state?

Answer 1

In my opinion, no, self-destruct is usually not a good practice. As you say, it creates dangerous voids on the blockchain where:

1. no one has a signing key,
2. there is no contract code, and
3. possibly users believe there is a contract there.

Any funds sent to such an address will be unrecoverable which is the same as destroyed.

A conscientious developer can completely disable a contract without creating such a void.

contract Pausable is Ownable {

  bool public isRunning;

  modifier onlyWhenRunning {
    require(isRunning);
    _;
  }

  function stopContract() public onlyOwner {
    isRunning = false;
  }
}

Check out OpenZeppelin for a more complete implementation of the pattern.

Hope it helps.

Answer 2

You can implement this functionality by yourself. You can implement a modifier before the selfdestruct instruction to check the quantity of ether owned by the contract. This way, the contract could be "destroyed" only if it does not own ether.