language-agnostic - 类型和类别有什么区别？

Question

什么使类型不同于类，反之亦然？

(在与语言无关的一般意义上)

Answer 1

以下答案来自Gof书( Design Patterns )

An object's class defines how theobject is implemented. The classdefines object's internal state andthe implementation of itsoperations.

In contrast, an object'stype only refers to its interface - aset of requests to which it canrespond.

An object can have many types,and objects of different classes canhave the same type.

//example in c++
template<typename T> 
const T & max(T const &a,T const &b)
{
return a>b?a:b;  //> operator of the type is used for comparison
}

max 函数需要一个具有操作> 的类型，并以其自己的类型作为其接口(interface)之一，任何满足上述要求的类都可以用于生成特定的 max<特定类/原始类型> 函数那个类(class)。