Any function object that is a class attribute defines a method for instances of that class. 类属性中的任何函数对象在类实例中都定义为方法。
This type of object is known as a functor or function object. 这种类型的对象称为functor或者functionobject。
Methods also support accessing ( but not setting ) the arbitrary function attributes on the underlying function object. 方法也支持访问(不是设置)的其实际所调用的函数的任意属性。
Notice that then, in the body of the loop, I use callback to invoke the passed parameter function object. 然后请注意,在循环体中,我使用callback来调用传递的参数函数对象。
So far, to use custom comparison functions, the standard practice has been to define your own function object and then define the operator () appropriately. 到目前为止,要想使用定制的比较函数,标准的做法是定义自己的函数对象,然后适当地定义操作符()。