I primarily work in C# and access modifiers allow me to constrain which types or their members on it are accessible to other types or assemblies.
This is particularly useful when authoring libraries as I know that for anything not public, I can refactor to my hearts content (provided the externally observed behaviour is otherwise unchanged).
It’s a bit of a pity that it was only relatively recently that Visual Studio changed the template for new classes to use internal instead of public.
There are lots of public classes in codebases I work on which are probably only public due to the old default and not used externally so could be refactored, but it’s hard to be sure.
Whereas with internal classes I can be sure (unless someone has used reflection, but then that’s their problem).
This is particularly useful when authoring libraries as I know that for anything not public, I can refactor to my hearts content (provided the externally observed behaviour is otherwise unchanged).
It’s a bit of a pity that it was only relatively recently that Visual Studio changed the template for new classes to use internal instead of public.
There are lots of public classes in codebases I work on which are probably only public due to the old default and not used externally so could be refactored, but it’s hard to be sure.
Whereas with internal classes I can be sure (unless someone has used reflection, but then that’s their problem).