C ++中堆对象获取器/设置器的更好实践 [英] Better practice for heap object getters / setters in C++

问题描述

我目前有

Type1 &GetType1() const
{
    return *this->type1;
}

void SetType1(const Type1 &type1)
{
    *this->type1 = type1;
}

以及类定义中

class Type2
{
    public:
        Type2();
        virtual ~Type2();
        Type1 &GetType1() const;
        void SetType1(const Type1 &type1);
    private:
        Type1 *type1 = nullptr;

}

主要

 int main()
 { 
       Type2 *type2 = new Type2();
       Type1 *newType1 = new Type1();
       type2->SetType1(*newType1);

       delete type2;
       delete newType1;
  }

我项目中的任何地方.在我看来这不是一个非常安全的方法，在某些情况下该对象指向NULL等. 我想知道是否有更好的普遍接受的方法可以做到这一点.也许操作超载是个好主意?

解决方案

如果您的类的成员指针可以为null，则只需从getter函数返回该指针，并让用户担心出现极端情况.

Type1* GetType1(){
  return this->type1;
}

void SetType1(Type1* type1) {
  this->type1 = type1;
}

如果该成员有可能实际上无法变为null(这是类不变的)，那么我认为返回引用并在getter中使用断言是一个好习惯.

I'm currently having

Type1 &GetType1() const
{
    return *this->type1;
}

void SetType1(const Type1 &type1)
{
    *this->type1 = type1;
}

and in the class definition

class Type2
{
    public:
        Type2();
        virtual ~Type2();
        Type1 &GetType1() const;
        void SetType1(const Type1 &type1);
    private:
        Type1 *type1 = nullptr;

}

And in main

 int main()
 { 
       Type2 *type2 = new Type2();
       Type1 *newType1 = new Type1();
       type2->SetType1(*newType1);

       delete type2;
       delete newType1;
  }

everywhere in my project. It seems to me that this is not a very safe method, there are cases in which the object is pointing to NULL, etc.. I would like to know if there is a better commonly accepted way to do that. Maybe opperation overloading is a good idea?

解决方案

If your class has a member pointer that can be null, then simply return the pointer from the getter function and have the user worry about the corner cases.

Type1* GetType1(){
  return this->type1;
}

void SetType1(Type1* type1) {
  this->type1 = type1;
}

If, by any chance the member cannot actually ever become null, which is a class invariant, then I think it is a good practice to return a reference, and use assertion in the getter.

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