What are the Advantages of Using `= default` for Default Constructors in C 11?

The "= default" Syntax in C 11: A Closer Examination

In C 11, the "= default" syntax was introduced to provide an explicit and uniform way to define default constructors, copy constructors, move constructors, and destructors. This article delves into the purpose and implications of this syntax, addressing a specific query regarding its advantages over the traditional empty constructor.

Understanding "= default" for Default Constructors

The "= default" syntax specifically defines a default constructor to have the same behavior as a user-defined default constructor with no initialization list and an empty compound statement. However, providing an empty implementation via the user-defined constructor affects the properties of the class.

Aggregates, Trivial Types, and "= default"

A user-defined constructor, even an empty one, makes the class non-aggregate and non-trivial. Using "= default" ensures that the class remains an aggregate or a trivial type, as desired. This is especially important for classes that require special optimization or interoperability with legacy code.

constexpr and Exception Specifications

Furthermore, "= default" provides control over the constexpr status and exception specifications of default constructors. By explicitly defaulting a constructor, you can make it constexpr and specify the exception specification that the implicit constructor would have.

Uniformity and Readability

Using "= default" promotes uniformity in defining special member functions. By using the same syntax for default constructors, copy constructors, move constructors, and destructors, your code's intent becomes more explicit and easier to read.

Conclusion

In conclusion, the "= default" syntax serves a specific purpose in C 11 by providing an explicit and uniform way to define default constructors and other special member functions. Its use allows for precise control over class properties and constructor behavior, enhancing code readability and maintainability.

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