Skip to content

Instantly share code, notes, and snippets.

What would you like to do?
Created using remix-ide: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at
// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.8.0;
* @title Owner
* @dev Set & change owner
contract Owner {
address private owner;
// event for EVM logging
event OwnerSet(address indexed oldOwner, address indexed newOwner);
// modifier to check if caller is owner
modifier isOwner() {
// If the first argument of 'require' evaluates to 'false', execution terminates and all
// changes to the state and to Ether balances are reverted.
// This used to consume all gas in old EVM versions, but not anymore.
// It is often a good idea to use 'require' to check if functions are called correctly.
// As a second argument, you can also provide an explanation about what went wrong.
require(msg.sender == owner, "Caller is not owner");
* @dev Set contract deployer as owner
constructor() {
owner = msg.sender; // 'msg.sender' is sender of current call, contract deployer for a constructor
emit OwnerSet(address(0), owner);
* @dev Change owner
* @param newOwner address of new owner
function changeOwner(address newOwner) public isOwner {
emit OwnerSet(owner, newOwner);
owner = newOwner;
* @dev Return owner address
* @return address of owner
function getOwner() external view returns (address) {
return owner;
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment