Can the C Standard Library Be Extended Through Inheritance?

Extending the Standard Library through Inheritance

The belief that the C standard library is generally not intended to be extended through inheritance has been widely held. However, upon closer examination, it becomes apparent that certain aspects of the library were indeed designed for this purpose.

Intended Extension Points in the Standard Library

One such component is the std::exception class. It is explicitly intended to be inherited from, allowing for the creation of custom exception types. When doing so, certain guidelines should be considered:

• Virtual Methods: Classes intended for inheritance should have virtual methods, which std::exception possesses.
• Friend Declarations: Excessive friend declarations can indicate encapsulation issues, suggesting against inheritance.
• Templates: Templates provide flexibility through specialization, often reducing the need for inheritance.
• Policy Mechanisms: Inheritance from classes with policy-based mechanisms (e.g., std::char_traits) is generally not advisable.

Interface Adherence When Extending

As a best practice, when inheriting from standard library classes, it is important to adhere to the interface defined in the ISO Standard. This means that, for instance, an inherited exception class's what() member function should return a narrow-text string (NTBS), ensuring compatibility with functions expecting a std::exception. While a program using an exception class with a non-standard-conforming what() function may technically still compile, it deviates from the intended purpose and introduces potential compatibility issues.

The above is the detailed content of Can the C Standard Library Be Extended Through Inheritance?. For more information, please follow other related articles on the PHP Chinese website!