How Can CRTP Be Used to Eliminate Virtual Function Overhead in C ?

Static Polymorphism with CRTP to Eliminate Virtual Function Overhead

In C , virtual member functions can incur runtime overhead due to dynamic dispatch. CRTP (Curiously Recurring Template Pattern) provides a mechanism to avoid this overhead and achieve static polymorphism.

CRTP to Enforce Interface

One approach is to enforce the interface statically by directly embedding the base class into the derived class and specifying the interface in the base class template:

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

struct my_type : base<my_type> {
  void foo() {};
};</code>

By doing this, each derived class becomes responsible for implementing its own foo() function. This ensures that the base class virtual function is no longer needed at runtime.

Compile-Time Type Deduction

Another technique is to avoid using pointer-to-base or reference-to-base idioms and perform the wiring at compile-time. By using template functions that deduce the derived class type at compile-time, static dispatch can be achieved:

<code class="cpp">template <class T>
void bar(base<T> &obj) {
  obj.foo(); // will do static dispatch
}</code>

This eliminates the need for dynamic dispatch and allows for optimized performance. So, by combining the interface definition and compile-time type deduction, CRTP enables static polymorphism and reduces the runtime overhead associated with dynamic polymorphism.

The above is the detailed content of How Can CRTP Be Used to Eliminate Virtual Function Overhead in C ?. For more information, please follow other related articles on the PHP Chinese website!