Is there a Python method to access all non-private and non-builtin attributes of a class?

I would like to call a method to give me a dict of all of the “non-private” (I use the term “private” somewhat loosely here since it does not really exist in Python) and non-builtin attributes (i.e. those that do not begin with a single or double underscore) on a class. Something like vars(MyClass) that would return only the “public” attributes on that class.

I’m aware that

from M import * 

does not import objects whose name starts with an underscore. (http://www.python.org/dev/peps/pep-0008/#id25) How does import implement that? Via a builtin function or just by checking for underscores? What is the pythonic way to do this?

Example:

class MyClass(object):
    def __init__(self):
        do_stuff()
    def _private(self):
        print 'private'
    def __gets_name_mangled(self:
        print 'becomes _MyClass__gets_name_mangled()'
    def public(self):
        print 'public'

If I do

vars(MyClass).keys()

I get

['_MyClass__gets_name_mangled', '__module__', '_private', '__doc__', '__dict__', '__weakref__', 'public', '__init__']

How can I get only

['public']

Or do I just need to check for underscores myself? It just seems like there would be a pythonic way to do this.

For more on underscores and double underscores, see:
What is the meaning of a single- and a double-underscore before an object name?

Best answer

Actually, it would be unpythonic for such function to exists – because “officially” there is no private or protected fields/properties in Python.

While it makes sense to throw away module attributes with leading underscores (which are usually some implementation details) during import * from some module*, it is not useful in context of any other object.

So, if you need to list only “public” methods/attributes of an object, just iterate through result of dir and drop names with leading underscores.


* “during import * from some module’”

Usually it is not the best practice. Consider the next example:

module A has a1 and a2 defined

module B has b1 and b2 defined

This code in module C works as expected:

from A import a1, a2
from B import *

Imagine we add function a1 in module B. Now suddenly module C is broken, although we haven’t touched it.