为什么要明确删除构造函数？ [英] why explicitly delete the constructor?

问题描述

何时/为什么要显式删除我的构造函数？假设原因是为了防止其使用，为什么不让它 private ？

When/why would I want to explicitly delete my constructor? Assuming the reason is to prevent its usage, why not just make it private?

class Foo
{ 
  public: 
    Foo() = delete; 
};

$ b

谢谢！

Thanks!

推荐答案

如何：

//deleted constructor
class Foo
{ 
  public: 
    Foo() = delete;     
  public:
    static void foo();
};

void Foo::foo()
{
   Foo f;    //illegal
}

对比

//private constructor
class Foo
{ 
  private: 
    Foo() {}     
  public:
    static void foo();
};

void Foo::foo()
{
   Foo f;    //legal
}

它们基本上是不同的。 private 告诉你只有类的成员可以调用该方法或访问该变量（当然是朋友）。在这种情况下，该类（或任何其他成员）的 static 方法调用 private 构造函数的类。

They're basically different things. private tells you that only members of the class can call that method or access that variable (or friends of course). In this case, it's legal for a static method of that class (or any other member) to call a private constructor of a class. This doesn't hold for deleted constructors.

范例这里。

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