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From: Peter Otten <__peter__@web.de>
Subject: Re: Correct type for a simple "bag of attributes" namespace object
Date: Sun, 03 Aug 2014 11:37:04 +0200
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Xref: csiph.com comp.lang.python:75584

Albert-Jan Roskam wrote:

> I find the following obscure (to me at least) use of type() useful exactly
> for this "bag of attributes" use case:
>>>> employee = type("Employee", (object,), {})
>>>> employee.name = "John Doe"
>>>> employee.position = "Python programmer"
>>>> employee.name, employee.position, employee
> ('John Doe', 'Python programmer', <class '__main__.Employee'>)
 
Are you sure you know what you are doing? The above is equivalent to

>>> class employee:
...     name = "John Doe"
...     position = "Python programmer"
... 
>>> employee.name, employee.position, employee
('John Doe', 'Python programmer', <class '__main__.employee'>)
>>> type(employee)
<class 'type'>

Basically you are using classes as instances. While there is no fundamental 
difference between classes and instances in Python you'll surprise readers 
of your code and waste some space:

>>> import sys
>>> sys.getsizeof(employee)
976
>>> class Employee: pass
... 
>>> employee = Employee()
>>> employee.name = "John Doe"
>>> employee.position = "Python programmer"
>>> sys.getsizeof(employee)
64