In C++, a deleted function is a member function that has been explicitly marked as deleted using the delete keyword. The purpose of a deleted function is to prevent its usage, either to enforce certain design constraints or to avoid ambiguous or unsafe scenarios.

When a deleted function is referenced, it results in a compile-time error, indicating that the function cannot be called or used in any way. This helps in catching potential issues during the compilation process itself.

Usage of Deleted Functions

Here’s an example that illustrates the usage of deleted functions in C++:

class NonCopyable {
public:
    NonCopyable() = default;
    NonCopyable(const NonCopyable&) = delete;             // Delete copy constructor
    NonCopyable& operator=(const NonCopyable&) = delete;  // Delete copy assignment operator

    // Other member functions...
};

int main() {
    NonCopyable obj1;
    NonCopyable obj2(obj1);             // Error: attempting to copy construct obj2 from obj1
    NonCopyable obj3;
    obj3 = obj1;                        // Error: attempting to copy assign obj1 to obj3

    return 0;
}

In the above example, the class NonCopyable contains deleted copy constructor and copy assignment operator. By doing so, we explicitly prevent the creation of new objects through copying.

Attempting to copy construct obj2 from obj1 or copy assign obj1 to obj3 will result in compile-time errors. This helps in enforcing the intention of not allowing copying of objects of NonCopyable class.

Benefits and Use Cases

Deleted functions provide several benefits in C++ programming:

• Preventing unwanted operations: By deleting certain functions, we can restrict the usage of those functions, helping to prevent misuse and unintended behavior.
• Enforcing design constraints: Deleted functions can enforce specific design choices, such as disallowing object copying or preventing certain operations on specific instances.
• Avoiding ambiguity: In certain cases, the presence of a deleted function can help avoid ambiguous scenarios where multiple overloaded functions could potentially match the given arguments.

To conclude, deleted functions in C++ are useful tools for enforcing design constraints, preventing unwanted operations, and improving code clarity. Correctly using deleted functions in your codebase can help catch errors at compile-time and facilitate better software development practices.

#Cpp #DeletedFunctions