Shortest way of creating an object with arbitrary attributes in Python?

Question

Hey, I just started wondering about this as I came upon a code that expected an object with a certain set of attributes (but with no specification of what type this object should be).

One solution would be to create a new class that has the attributes the code expects, but as I call other code that also needs objects with (other) attributes, I'd have to create more and more classes.

A shorter solution is to create a generic class, and then set the attributes on instances of it (for those who thought of using an instance of object instead of creating a new class, that won't work since object instances don't allow new attributes).

The last, shortest solution I came up with was to create a class with a constructor that takes keyword arguments, just like the dict constructor, and then sets them as attributes:

class data:     def __init__(self, **kw):         for name in kw:             setattr(self, name, kw[name])  options = data(do_good_stuff=True, do_bad_stuff=False) 

But I can't help feeling like I've missed something obvious... Isn't there a built-in way to do this (preferably supported in Python 2.5)?

Answer 1

type('', (), {})() will create an object that can have arbitrary attributes.

Example:

obj = type('', (), {})() obj.hello = "hello" obj.world = "world" print obj.hello, obj.world   # will print "hello world" 

type() with three arguments creates a new type.

• The first argument '' is the name of the new type. We don't care about the name, so we leave it empty.

• The second argument () is a tuple of base types. Here object is implicit.

• The third argument is a dictionary of attributes of the new object. We start off with no attributes so it's empty {}.

In the end we instantiate a new instance of this new type with ().