Delegating Constructor

Delegating Constructor

What is delegating constructor?

Definition:one ctor can call another ctor

• 被构造函数放到主调构造函数初始化列表的位置
• 调用次序：A() → A(int) → A(int, int)

class A{
public:   
   A(): A(0){}
   A(int i): A(i, 0){}
   A(int i, int j) {
      num1=i;
      num2=j;
      average=(num1+num2)/2;
   }
private:
   int num1;
   int num2;
   int average;
};

Avoiding recursive calls of target constructors

• 递归调用：函数调用其本身
• 调用次序（调用环):A() → A(int) → A(int, int) → A()

class A{
public:   
   A(): A(0){}
   A(int i): A(i, 0){}
   A(int i, int j): A(){}
private:
   int num1;
   int num2;
   int average;
};

Adavantages

• Less code
• More clear code logic