C++ Best practices for constants

Question

I have a whole bunch of constants that I want access to in different parts of my code, but that I want to have easy access to as a whole:

static const bool d         


        

Answer 1

What is the problem with this usage?
Do not declare a static type in header file, It does not do what you think it does.

When you declare a static in header file a copy of that variable gets created in each Translation Unit(TU) where you include that header file, SO each TU sees a different variable, this is opposite to your expectation of having a global.

Suggested Solution:
You should declare them as extern in a header file and define them in exactly one cpp file while include the header with extern in every cpp file where you want to access them.

Good Read:
How should i use extern?