Which one is the most readable?
I think the snake case version is much more readable than the camel case.
How we name our functions is not a technical choice, it’s a convention. Nobody can say that the snake case version is worse than the camel case one. The people from the PSR committee decided a long time ago that, in PHP, methods will be named in camel case and classes will be named in studly case. But in Rust, or in Python, a different choice was made: it’s snake case for functions and methods.
Don’t let other people decide what works best for you. Recently, I started using snake case for all my functions, methods and variables. And I think I’ll switch to the
Siret_Number approach for all my classes.