Question

In Python, can an object have another object as an attribute? For example, can a class called car have a class called tire as an attribute?

Answer 1

Do you mean a class tire or an instance of class tire? It can have both although the latter is probably more useful. If you’re looking for an object of class Mary to has-a object of type Fred you’d want the classinst variety of assignment:

Python 2.6.5 (r265:79063, Apr 16 2010, 13:09:56) 
>>> class Fred(object): pass
... 
>>> class Mary(object):
...     def __init__(self):
...         self.classref = Fred
...         self.classinst = Fred()
... 
>>> x = Mary()
>>> dir(x)
[... 'classinst', 'classref']
>>> x.classref
<class '__main__.Fred'>
>>> x.classinst
<__main__.Fred object at 0xb76eed0c>