Disallowcopy in C++

Disallowcopy is a technique used in C++ programming to prevent objects from being copied. In C++, objects can be copied by the copy constructor or the assignment operator. However, there may be situations where we want to disallow the copying of objects. This can be accomplished by writing the copy constructor and assignment operator as private with no implementation.

Why use disallowcopy?

There are several reasons why one may want to disallow copying of objects:

• Prevent multiple objects from holding the same resource, such as a file or socket.
• Help enforce the single responsibility principle and prevent objects from having multiple roles.
• Improve performance by avoiding unnecessary copies of large objects.

How to use disallowcopy

To use disallowcopy, simply declare the copy constructor and assignment operator as private with no implementation. Here's an example:

class MyClass {
public:
    // Public constructor and other functions
    MyClass();
    void doSomething();

private:
    // Private copy constructor and assignment operator
    MyClass(const MyClass&);
    MyClass& operator=(const MyClass&);
};

In the example above, we've declared the copy constructor and assignment operator as private. This means that they can only be called from within the class itself and cannot be accessed from outside the class. Attempting to copy an object of this class will result in a compile-time error.

Conclusion

Disallowing object copying can be a useful technique for improving code quality and preventing bugs. By using the Disallowcopy technique, we can ensure that objects cannot be copied, leading to more robust and maintainable code.