September 25, 2020 noncopyable of boost library for singleton mode

from boost::noncopyable Class inheritance

reason ：

For singleton singleton object . When a class does not explicitly declare a constructor 、 Destructor 、 copy constructor 、 When assigning a constructor , The compiler generates by default , But sometimes we don't want them to have the ability to be copied or assigned .

Class ：8 individual
https://editor.csdn.net/md/?articleId=108996157

Internal implementation ：

Private copy constructor and assignment constructor , Subclass objects cannot be copied and assigned to other objects

//C++98 Is declared private 
class noncopyable{
    
protected:
	noncopyable() {
    }
	~noncopyable() {
    }
private:
	noncopyable( const noncopyable& ){
    };
	const noncopyable& operator=( const noncopyable& ){
    return *this};
};
//c++11 of use delete Indicates no use ,default Means no action is taken 
 class noncopyable{
    
protected:
    noncopyable() = default;
    ~noncopyable() = defalult;
    noncopyable(const noncopyable &) = delete;
    noncopyable& operator=(const noncopyable& ) = delete;
};

give an example ：

#include <boost/noncopyable.hpp>
using namespace boost;
class test:public boost::noncopyable {
    
};

int main() {
    
    test a, c;
    test b(c); // Error. copy constructor 
    a = c;// Error. The mutator 
    return 0;
}