再次分析delegatecall和call的区别

在之前的文章中，已经详细介绍了delegatecall和call的用法, 原文： EIP1967-实现可升级智能合约

---

delegatecall:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

// NOTE: Deploy this contract first
contract B {
    // NOTE: storage layout must be the same as contract A
    uint public num;
    address public sender;
    uint public value;

    function setVars(uint _num) public payable {
        num = _num;
        sender = msg.sender;
        value = msg.value;
    }
}

contract A {
    uint public num;
    address public sender;
    uint public value;

    function setVars(address _contract, uint _num) public payable {
        // A's storage is set, B is not modified.
        (bool success, bytes memory data) = _contract.delegatecall(
            abi.encodeWithSignature("setVars(uint256)", _num)
        );
    }
}

调用合约A的setVars函数，setVars合约内会以delegatecall的方式调用合约B, 更确切地说是合约A将合约B的setVars函数代码加载到合约A的运行环境，因此，就很容易理解setVars修改的是合约A中的数据，而不是合约B中的数据了。

call

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

// NOTE: Deploy this contract first
contract B {
    // NOTE: storage layout must be the same as contract A
    uint public num;
    address public sender;
    uint public value;

    function setVars(uint _num) public payable {
        num = _num;
        sender = msg.sender;
        value = msg.value;
    }
}

contract A {
    uint public num;
    address public sender;
    uint public value;

    function setVars(address _contract, uint _num) public payable {
        // A's storage is set, B is not modified.
        (bool success, bytes memory data) = _contract.call(
            abi.encodeWithSignature("setVars(uint256)", _num)
        );
    }
}