异常处理

try...catch... / throw

function tryCatchExternalCall(uint _i) public {
  try foo.myFunc(_i) returns (string memory result) {
    // ...
  } catch {
    // ...
  }
}

require / revert / assert

contract A {
  function testRequire(uint _i) public pure {
    require(_i > 10, '_i error'); // 当 _i <= 10报错
  }
  function testRevert(uint _i) public pure {
    if (_i > 10) {
      revert('i need to be greater than 10'); // 不满足条件主动触发错误
    }
  }
  function testAssert(uint _i) public pure {
    assert(_i == 100); // 不满足assert内部条件的报错
  }
}

自定义错误

contract A {
  // 定义错误
  error MyError(address caller, uint i);

  function testCustomeError(uint _i) public view {
    if (_i > 10) {
      revert MyError(msg.sender, _i)
    }
  }
}