onHover：(something) => function(context)和flutter中的onHover: function(context)有什么不同？

Question

当我执行onHover: function(context)时，它会给出错误

但是onHover: (event) => function(context)运行得很好。

有什么区别？onHover应该总是有一个变量(PointerHoverEvent)吗？

Answer 1

function(context);

可能会返回onHover参数不想要的东西，onHover参数想要一个函数，在这里onHover: (event) => function(context)你给它的是参数想要的函数，

给你一个概念

//this is a function
Function functionWhichReturnsInt = (){return 1;};

//this is function which needs function
void feedMeAFunction(Function food){
  food();
}

//this is a function which needs int
void feedMeAnInt(int food){
  print(food);
}

//we can call the functions like this
//passing a function
feedMeAFunction(functionWhichReturnsInt);
//passing an int
feedMeAnInt(functionWhichReturnsInt());