Why is the 'typedef super' idiom so commonly used in C ?

Using "super" in C

Introduction

In C , the use of the "typedef super" idiom to enable access to the base class as "super" has become a common practice, especially among experienced programmers. This idiom involves creating a typedef within a derived class that references the base class. Here's a brief explanation of how it works and the benefits it offers:

How It Works

The following code demonstrates the "typedef super" idiom:

class Derived : public Base {
    typedef Base super;  // Creates an alias for Base

With this typedef, you can use the "super" alias to access the base class in various scenarios, such as in constructors:

Derived(int i, int j) : super(i), J(j) {}

or when calling methods of the base class within overridden versions:

void Derived::foo() {
    super::foo();  // Calls the overridden version of foo in Derived
}

The idiom can be used for chaining, allowing access to the base class of the base class:

class DerivedDerived : public Derived {
    typedef Derived super;  // Creates an alias for Derived

void DerivedDerived::bar() {
    super::bar();  // Calls Derived::bar
    super::super::bar;  // Calls Base::bar
}

Benefits

The "typedef super" idiom offers several benefits:

• Code Readability: It makes the code more readable and clear by providing a convenient alias for the base class, especially when the base class is verbose or templated.
• Consistent Syntax: Using "super" allows for consistent syntax across different scenarios, such as constructors, methods, and chained base classes.

Commonality and Standardization

While the "typedef super" idiom has become fairly common, it is still considered a non-standard feature in C . However, the discussion mentioned in the answer suggests that the concept was initially considered for inclusion in the language.

Conclusion

The "typedef super" idiom is a useful technique that enhances code readability and consistency within C programs. It is widely used and has been implemented by programmers to emulate the functionality of the "super" keyword found in other languages. Although not standardized, this idiom remains a valuable tool for experienced C developers.

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