How to create objects on the fly in python?

Question

How do I create objects on the fly in Python? I often want to pass information to my Django templates which is formatted like this:

{\'test\': [a1, a2, b2],          


        

Answer 1

Use collections.namedtuple.

Answer 2

Here's a rogue, minimalist way to create an object. A class is an object, so just commandeer the class definition syntax as if it were a Python object literal:

class testobj(object):
    test = [a1,a2,b2]
    test2 = 'something else'
    test3 = 1

Class variables are the members of the object, and are easily referenced:

assert testobj.test3 == 1

This is weird, a class never used as a class: it's never instantiated. But it's a low-clutter way to make an ad hoc, singleton object: The class itself is your object.

Answer 3

There is another solution in Python 3.3+ types.SimpleNamespace

from types import SimpleNamespace
test_obj = SimpleNamespace(a=1, b=lambda: {'hello': 42})

test_obj.a
test_obj.b()

Answer 4

use building function type: document

>>> class X:
...     a = 1
...
>>> X = type('X', (object,), dict(a=1))

first and second X are identical

Answer 5

In Django templates, the dot notation (testobj.test) can resolve to the Python's [] operator. This means that all you need is an ordinary dict:

testobj = {'test':[a1,a2,b2], 'test2':'something else', 'test3':1}

Pass it as testobj variable to your template and you can freely use {{ testobj.test }} and similar expressions inside your template. They will be translated to testobj['test']. No dedicated class is needed here.

Answer 6

The code below also require a class to be created however it is shorter:

 >>>d = {'test':['a1','a2','b2'], 'test2':'something else', 'test3':1}
 >>> class Test(object):
 ...  def __init__(self):
 ...   self.__dict__.update(d)
 >>> a = Test()
 >>> a.test
 ['a1', 'a2', 'b2']
 >>> a.test2
 'something else'