go interface 入门

code explame

如下所示为一个interface的代码示例。那么要如何理解这个interface呢，官方说的是interface是一组方法签名的集合,谁实现了这个签名集合的所有方法，谁就实现了这个interface。代码&用例图如下所示

package main

import "fmt"

type People interface {
	name(name string)
	age(age int)
}

type Student struct {
	score uint
}

type Teacher struct {
}

func (s *Student) name(nm string) {
	fmt.Println("Student name is %s ", nm)
}

func (s *Student) age(age int) {
	fmt.Println("Student age is ", age)
}

func (t *Teacher) name(nm string) {
	fmt.Println("Teacher name is  ", nm)
}

func (t *Teacher) age(age int) {
	fmt.Println("Teacher age is ", age)
}

// 定义interface变量
var conn People

func GetStudentConn() People {
	conn = &Student{score: 100}
	return conn
}

func GetTeacherConn() People {
	conn = &Teacher{}
	return conn
}

func main() {
	stuConn := GetStudentConn()
	stuConn.age(100)

	teaConn := GetTeacherConn()
	teaConn.name("tea")
}
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在本人看来，go的interface有点像cpp中的抽象类这种概念，cpp的抽象类是指抽象类只定义纯虚函数的签名,由其子类具体实现这些函数的签名，只有在main函数中具体调用的时候才知道具体是哪个子类发生的行为(也有人说go的interface像cpp的多态，本人对比了下，cpp的多态是指基类指针指向子类对象，从而使得虚函数指针指向子类对象虚表发生调用的行为，个人认为不像，欢迎大家讨论)

class Shape 
{
public:
   // 提供接口框架的纯虚函数
   virtual int getArea() = 0;
   void setWidth(int w)
   {
      width = w;
   }
   void setHeight(int h)
   {
      height = h;
   }
protected:
   int width;
   int height;
};
 
// 派生类
class Rectangle: public Shape
{
public:
   int getArea()
   { 
      return (width * height); 
   }
};
class Triangle: public Shape
{
public:
   int getArea()
   { 
      return (width * height)/2; 
   }
};
int main(void)
{
   Rectangle Rect;
   Triangle  Tri;
 
   Rect.setWidth(5);
   Rect.setHeight(7);
   // 输出对象的面积
   cout << "Total Rectangle area: " << Rect.getArea() << endl;
 
   Tri.setWidth(5);
   Tri.setHeight(7);
   // 输出对象的面积
   cout << "Total Triangle area: " << Tri.getArea() << endl; 
 
   return 0;
}
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