CRTP: Can Static Dispatch Replace Dynamic Polymorphism in C ?

CRTP: An Alternative to Dynamic Polymorphism

Dynamic polymorphism, while providing flexibility, can often lead to runtime overhead due to the use of virtual member functions. Fortunately, C offers an effective alternative: Curiously Recurring Template Pattern (CRTP).

CRTP allows you to achieve static dispatch, similar to polymorphism, but without the overhead of virtual member functions. This is accomplished through type specialization and template deduction.

Method 1: Static Interface Specification

By specifying the interface statically for your derived types, you can enforce certain behaviors at compile time. For instance, consider the following code snippet:

<code class="cpp">template <class Derived>
struct base {
    void foo() {
        static_cast<Derived *>(this)->foo();
    };
};</code>

In this scenario, base<> requires any derived type to define a foo() member function for compilation. Each derived type, such as my_type and your_type, must implement their own foo() function to meet this requirement.

Method 2: Compile-Time Type Deduction

Alternatively, you can avoid using pointers or references to the base class and perform type wiring at compile time. Consider the following template function:

<code class="cpp">template <class T> // T is deduced at compile-time
void bar(base<T> &obj) {
    obj.foo(); // does static dispatch
}</code>

This function accepts a reference to an object of type base, where T is deduced from the actual object passed at compile time. This allows for static dispatch based on the actual derived type.

Advantages of CRTP

• Static dispatch: Eliminates the runtime overhead of dynamic polymorphism.
• Implements interfaces at compile time: Enforces behavior consistency among derived classes.
• Excellent for binary size optimization and performance: Removes the need for virtual tables and type information.

By leveraging CRTP, you can achieve static polymorphism in C , avoiding the drawbacks of dynamic polymorphism while preserving the benefits of object-oriented design.

The above is the detailed content of CRTP: Can Static Dispatch Replace Dynamic Polymorphism in C ?. For more information, please follow other related articles on the PHP Chinese website!