Python name mangling

Question

In other languages, a general guideline that helps produce better code is always make everything as hidden as possible. If in doubt about whether a variable should be privat

Answer 1

I wouldn't say that practice produces better code. Visibility modifiers only distract you from the task at hand, and as a side effect force your interface to be used as you intended. Generally speaking, enforcing visibility prevents programmers from messing things up if they haven't read the documentation properly.

A far better solution is the route that Python encourages: Your classes and variables should be well documented, and their behaviour clear. The source should be available. This is far more extensible and reliable way to write code.

My strategy in Python is this:

1. Just write the damn thing, make no assumptions about how your data should be protected. This assumes that you write to create the ideal interfaces for your problems.
2. Use a leading underscore for stuff that probably won't be used externally, and isn't part of the normal "client code" interface.
3. Use double underscore only for things that are purely convenience inside the class, or will cause considerable damage if accidentally exposed.

Above all, it should be clear what everything does. Document it if someone else will be using it. Document it if you want it to be useful in a year's time.

As a side note, you should actually be going with protected in those other languages: You never know your class might be inherited later and for what it might be used. Best to only protect those variables that you are certain cannot or should not be used by foreign code.