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January 26, 2022 05:45
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Created using remix-ide: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at https://remix.ethereum.org/#version=soljson-v0.8.7+commit.e28d00a7.js&optimize=false&runs=200&gist=
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// SPDX-License-Identifier: GPL-3.0 | |
pragma solidity >=0.7.0 <0.9.0; | |
/** | |
* @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; | |
} | |
} |
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