[[nodiscard]] - A useful C++17 feature.

In C++, the [[nodiscard]] attribute is a C++17 feature that can be applied to the declaration of a function, class, or enumeration. It serves as a hint to the compiler and to developers that the return value of the annotated entity should not be ignored.

When [[nodiscard]] is used, it indicates that the return value of the function or the instantiation of the class or enumeration should be checked or used in some way. It helps prevent potential bugs and mistakes where the return value is unintentionally ignored, which can lead to undesirable behavior or incorrect program execution.

For example, consider a function

int calculateSum(int a, int b);

that calculates the sum of two integers and returns the result. If this function is marked with [[nodiscard]] like

[[nodiscard]] int calculateSum(int a, int b);

the compiler can emit a warning or an error if the return value is not utilized. This serves as a reminder for the developer to handle the return value appropriately.

Here's an example usage of [[nodiscard]] with a class:

[[nodiscard]] class MyObject {

??// class definition

};

In this case, when an instance of MyObject is created, the compiler can provide a warning if the object's creation is not assigned to a variable or used in any way.

It's important to note that the [[nodiscard]] attribute is not mandatory, and it is up to the developer to decide whether to use it based on their specific needs and code style guidelines. Some compilers may treat it as a warning, while others may treat it as an error.

Read more: https://programminggyan.com/nodiscard-when-to-use-modern-c-tip/

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