Say I have this contract:
contract Foo { uint256 public foo; function setFoo(uint256 _foo) public { foo = _foo; } function setFooToZero() public { foo = 0; } } And I want to inherit from it like so:
contract Bar is Foo { function setFooToZero() public {} } This way, setFooToZero gets updated to a function that does nothing, but is there a way of disabling it? Of not having it in the bytecode of the contract at all?
Child contract can't "erase" functionality from the parent contract. It can only override it.
So the only things you can do is set some boolean flag to disable functionality in parent function or simply override the functionality with your own implementation. Of course nothing prevents someone from using the parent contract directly without your tricks so they'd get the full parent functionality in use - unless these functions are marked as internal.
No, but sort of.
A contract that inherits (Bar) is committed to implementing all functions defined in the parent (Foo), so you can't make the function disappear.
Functions can be overridden, as you have discovered. You can also give the function private visibility which makes it inaccessible to child contracts.
Your empty function will do nothing. It will also return "success" and allow the caller to continue as normal. That is either desirable or undesirable depending on the purpose of the function. In most cases, the desirable thing to do would be to revert. It's an abstract example, so abstract guidance. ;-)
function setFooToZero() public { revert("disabled"); } Hope it helps.
Foo(seriously). Why are you inheriting from a contract that has code in it you don't actually want? See also diligence.consensys.net/posts/2019/06/… for a more general rant about inheritance.