具有多个非默认构造函数基的Singleton派生类

Singleton Derived Class with multiple bases of non-default constructors

本文关键字：Singleton 派生 构造函数 默认      更新时间：2023-10-16

我有一个从多个基类派生的类，我想让它成为一个单例。问题是派生类和基类不使用默认构造函数和参数，所以我不知道如何管理。我希望能够将参数传递给构造函数，但我只希望可以传递一次(我不希望它是setter)。我唯一的解决方案是在派生类的getInstance()成员中使用静态布尔值。

基本情况：

//Singleton Derived Class with multiple bases of non-default constructors
class base1 {
public:
base1(int* value) :
val_{value} {;}
~base1();
private:
int val_;
}
class base2 {
public:
base2(int* value) :
val_{value} {;}
~base2();
private:
int val_;      
}
class derived : public base1, public base2 {
public:
derived(int* value) :
base1{value},   //Base 1 constructor call
base2{value},   //Base 2 constructor call
val_{value} {;}
~derived();
private:
int val_;
}
//Creation
derived newDerived(&value);

试着让它像单身汉一样？

//Lets make it a singleton
class base1 {
public:
base1(); //Can I pass the construtor anything?
~base1();
private:
int val_;
}
class base2 {
public:
base2(); //Can I pass the construtor anything?
~base2();
private:
int val_;      
}
class derived : public base1, public base2 {
public:
static derived& getInstance(int* value) {
static bool init;
if (!init) {
base1::val_ = value;
base2::val_ = value;
init=true;
}
static derived instance;
return instance;
}
derived(int* value) {;}
~derived();
private:
derived(derived const&) = delete;           //Copy construct
derived(derived&&) = delete;                //Move construct
derived& operator=(derived const&) = delete;//Copy assign
derived& operator=(derived &&) = delete;    //Move assign
int val_;
}
//Creation
derived::getInstance(&value);

我在寻找我应该如何做这件事的方向，或者我根本不应该这样做的原因？感谢

开始吧。我在这里使用指针而不是引用。这只是一个例子，因此我不会将这个单例作为线程安全的。还要将默认构造函数声明为private，这样它就不能实例化。

class base1 {
public:
base1(int* value) : val_(*value) {}
~base1() {};
private:
int val_;
};
class base2 {
public:
base2(int* value) :
val_(*value ) { }
~base2() {};
private:
int val_;
};
class derived : public base1, public base2 {
private:
derived(int* value) :
base1(value),   //Base 1 constructor call
base2(value),   //Base 2 constructor call
val_(*value) {}
~derived() {};
private:
int val_;
static derived* driv;
public:
static derived* getInstance(int* value);
};
derived* derived::driv = NULL;
derived* derived::getInstance(int* value)
{
if (driv == NULL)
{
driv = new derived(value);
}
return driv;
}
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