Modifiers are code that can be run before and / or after a function call.
수정자는 함수 호출 전후에 실행할 수 있는 코드입니다.
Modifiers can be used to:
수정자는 다음과 같이 사용할 수 있다.
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;
contract FunctionModifier {
// We will use these variables to demonstrate how to use
// modifiers.
address public owner;
uint public x = 10;
bool public locked;
constructor() {
// Set the transaction sender as the owner of the contract.
owner = msg.sender;
}
// Modifier to check that the caller is the owner of
// the contract.
modifier onlyOwner() {
require(msg.sender == owner, "Not owner");
// Underscore is a special character only used inside
// a function modifier and it tells Solidity to
// execute the rest of the code.
_;
}
// Modifiers can take inputs. This modifier checks that the
// address passed in is not the zero address.
modifier validAddress(address _addr) {
require(_addr != address(0), "Not valid address");
_;
}
function changeOwner(address _newOwner) public onlyOwner validAddress(_newOwner) {
owner = _newOwner;
}
// Modifiers can be called before and / or after a function.
// This modifier prevents a function from being called while
// it is still executing.
modifier noReentrancy() {
require(!locked, "No reentrancy");
locked = true;
_;
locked = false;
}
function decrement(uint i) public noReentrancy {
x -= i;
if (i > 1) {
decrement(i - 1);
}
}
}
Solidity - Constructor (0) | 2022.12.30 |
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