Adding internal function to set the owner of Ownable

[Amxx]

Some pattern require an Ownable contract to change its owner under specific condition. This would for example be necessary to implement an OwnableClaimable contract for #2369 on top of the existing Ownable.

However, the current implmentation of Ownable can only be transfered using the public transferOwnership, which has the modifier onlyOwner.

I believe it would be better to have two function, one internal that does the change, and one public that gives restricted access to the internal.

abstract contract Ownable is Context {
    ...
    function renounceOwnership() public virtual onlyOwner {
        _setOwnership(address(0));
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwnership(newOwner);
    }

    function _setOwnership(address newOwner) internal {
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

[pavlovdog]

Good point! What do you think about completely removing constructor in favor of internal function? My struggle is that contracts with constructor can't be used with proxy pattern. So I should create custom Ownable to use it in implementation contract.

I can make a PR if this thing make sense.

[Amxx]

Removing the constructor would break backward compatibility, so its a big no.

For upgradeable contract, you should use OwnableUpgradeable from the @openzeppelin/contract-upgradeable package

[frangio]

Fixed in 4.4.