How to get instance variables in Python?

Question

Is there a built-in method in Python to get an array of all a class' instance variables? For example, if I have this code:

class hi:
  def __init__(self):
    self.ii = "foo"
    self.kk = "bar"

Is there a way for me to do this:

>>> mystery_method(hi)
["ii", "kk"]

Edit: I originally had asked for class variables erroneously.

Answer 1

Both the Vars() and dict methods will work for the example the OP posted, but they won't work for "loosely" defined objects like:

class foo:
  a = 'foo'
  b = 'bar'

To print all non-callable attributes, you can use the following function:

def printVars(object):
    for i in [v for v in dir(object) if not callable(getattr(object,v))]:
        print '\n%s:' % i
        exec('print object.%s\n\n') % i

Answer 2

Every object has a __dict__ variable containing all the variables and its values in it.

Try this

>>> hi_obj = hi()
>>> hi_obj.__dict__.keys()

Answer 3

You can also test if an object has a specific variable with:

>>> hi_obj = hi()
>>> hasattr(hi_obj, "some attribute")

Answer 4

Your example shows "instance variables", not really class variables.

Look in hi_obj.__class__.__dict__.items() for the class variables, along with other other class members like member functions and the containing module.

class Hi( object ):
    class_var = ( 23, 'skidoo' ) # class variable
    def __init__( self ):
        self.ii = "foo" # instance variable
        self.jj = "bar"

Class variables are shared by all instances of the class.

Answer 5

Use vars()

class Foo(object):
    def __init__(self):
        self.a = 1
        self.b = 2

vars(Foo()) #==> {'a': 1, 'b': 2}
vars(Foo()).keys() #==> ['a', 'b']

Answer 6

Suggest

>>> print vars.__doc__
vars([object]) -> dictionary

Without arguments, equivalent to locals().
With an argument, equivalent to object.__dict__.

In otherwords, it essentially just wraps __dict__