73 lines
1.9 KiB
Solidity
73 lines
1.9 KiB
Solidity
// SPDX-License-Identifier: GPL-3.0
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pragma solidity >=0.8.2 <0.9.0;
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/**
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* @title Storage
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* @dev Store & retrieve value in a variable
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* @custom:dev-run-script ./scripts/deploy_with_ethers.ts
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*/
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contract Storage {
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address private owner;
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// event for EVM logging
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event OwnerSet(address indexed oldOwner, address indexed newOwner);
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// modifier to check if caller is owner
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modifier isOwner() {
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// If the first argument of 'require' evaluates to 'false', execution terminates and all
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// changes to the state and to Ether balances are reverted.
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// This used to consume all gas in old EVM versions, but not anymore.
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// It is often a good idea to use 'require' to check if functions are called correctly.
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// As a second argument, you can also provide an explanation about what went wrong.
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require(msg.sender == owner, "Caller is not owner");
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_;
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}
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/**
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* @dev Set contract deployer as owner
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*/
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constructor() {
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console.log("Owner contract deployed by:", msg.sender);
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owner = msg.sender; // 'msg.sender' is sender of current call, contract deployer for a constructor
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emit OwnerSet(address(0), owner);
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}
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/**
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* @dev Change owner
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* @param newOwner address of new owner
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*/
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function changeOwner(address newOwner) public isOwner {
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emit OwnerSet(owner, newOwner);
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owner = newOwner;
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}
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/**
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* @dev Return owner address
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* @return address of owner
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*/
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function getOwner() external view returns (address) {
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return owner;
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}
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uint256 number;
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/**
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* @dev Store value in variable
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* @param num value to store
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*/
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function store(uint256 num) public {
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number = num;
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}
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/**
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* @dev Return value
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* @return value of 'number'
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*/
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function retrieve() public view returns (uint256){
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return number;
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}
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}
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