#Keywords everywhere comp code#

Since immutability is a technical restriction, there is no technical downside to using it. What does вЂњFred const* pвЂќ mean?, C++ FAQ ()ДЄre there downsides to using immutability whenever possible?.If you still doubt that immutability is useful in C++ (or are just curious, which you should be), please read these: TurnerвЂ™s talk on the subject of practical performance: Jason Turner: Practical Performance Practices вЂ“ YouTube. Knowing that some values are immutable, the compiler will be able to make assumptions and use syntactic shortcuts.

#Keywords everywhere comp code#

The compiler can (and will) optimize the code according to the const directives. If you find yourself in a reliable code, where you are sure that const is used properly, then this keyword -or its absence- serves as an indication of the intended mutability of the variable. Then, you wonвЂ™t be able to inadvertently modify something you shouldnвЂ™t and you give insight to the compiler and the developers of the data you manipulate. What is called const-correctness in C++ is the fact that if you state that a given variable is immutable, then it wonвЂ™t be modified.Д¬onst-correctness is reached when you use the const keyword to tell when a variable wonвЂ™t be modified.

Some very good reasons to make your variables immutable Safety That is also another reason I wish to use the word immutable and not const. However, this article only refers to const as a way to render data immutable, so I would be grateful if you ignore situations where const does not refer to inherently immutable data. For instance, you can use the keyword const in a function prototype to indicate you wonвЂ™t modify it, but you can pass a mutable object as this parameter. Nota bene: in C++ the keyword const does not completely refer to immutability. To be a little more inclusive, I will use the words immutable and immutability instead of const and constness. const is a keyword used in some languages (C++, Javascript, etc.) but the concept of immutability exists in other languages (in some of them, there is even no keyword attached to the concept, like in Rust). However, the generic concept this article is about is actually called вЂњimmutabilityвЂќ, and not вЂњconstnessвЂќ. In the title, I used the word вЂњconstвЂќ because const is a keyword every C++ developer knows (I hope). Author: ChloГ© Lourseyre A bit of terminology