Python: Call a constructor whose name is stored in a variable [duplicate]

Question

I have the following variable:

var = 'MyClass'

I would like to create an object of MyClass based on the variable var. Something like var(). How can I do this in Python?

Answer 1

>>> def hello():
...     print "hello world"
... 
>>> globals()["hello"]()
hello world

Answer 2

Presuming you have the class' module as a variable as well, you can do the following, where the class you want "MyClass" resides in module "my.module":

def get_instance(mod_str, cls_name, *args, **kwargs):
    module = __import__(mod_str, fromlist=[cls_name])
    mycls = getattr(module, cls_name)

    return mycls(*args, **kwargs)


mod_str = 'my.module'
cls_name = 'MyClass'

class_instance = get_instance(mod_str, cls_name, *args, **kwargs)

This function will let you get an instance of any class, with whatever arguments the constructor needs, from any module available to your program.