Create an anonymous class instance in python

Question

Sometimes i need to create an anonymous class instance in python, just like c#:

var o= new {attr1=\"somehing\", attr2=344};

but in python i

Answer 1

type

while this is not precisely a single statement I think creating a wrapper around the magic of the accepted answer makes it by far more readable.

import inspect 

# wrap the type call around a function 
# use kwargs to allow named function arguments
def create_type(name, **kwargs):
    return type(name, (object,), kwargs)

# example call to make a structure
p = create_type('foobar', xxx='barfoo', seti=0)

assert p.xxx == 'barfoo'
assert p.seti == 0

print inspect.getmembers(p)

Output

[('__class__', ),
 ('__delattr__', ),
 ('__dict__', ),
 ('__doc__', None),
 ('__format__', ),
 ('__getattribute__', ),
 ('__hash__', ),
 ('__init__', ),
 ('__module__', '__main__'),
 ('__new__', ),
 ('__reduce__', ),
 ('__reduce_ex__', ),
 ('__repr__', ),
 ('__setattr__', ),
 ('__sizeof__', ),
 ('__str__', ),
 ('__subclasshook__', ),
 ('__weakref__', ),
 # here they are
 ('seti', 0),
 ('xxx', 'barfoo')]

namedtuple

from collections import namedtuple

d = { 'a' : 'foo', 'b' : 'bar' }
foobar = namedtuple('foobar', d.keys())(**d)
print foobar

Output

Python 2.7.5 (default, May 30 2013, 16:55:57) [GCC] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from collections import namedtuple
>>> d  =  { 'a' : 'foo', 'b' : 'bar' }
>>> foobar = namedtuple('foobar', d.keys())(**d)
>>> print foobar
foobar(a='foo', b='bar')
>>>