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Date: Sun, 3 Aug 2014 03:51:12 -0700
From: Albert-Jan Roskam <fomcl@yahoo.com>
Subject: Re: Correct type for a simple "bag of attributes" namespace object
To: Peter Otten <__peter__@web.de>, "python-list@python.org" <python-list@python.org>
In-Reply-To: <lrkvs1$6hk$1@ger.gmane.org>
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=0A=0A----- Original Message -----=0A=0A> From: Peter Otten <__peter__@web.=
de>=0A> To: python-list@python.org=0A> Cc: =0A> Sent: Sunday, August 3, 201=
4 11:37 AM=0A> Subject: Re: Correct type for a simple "bag of attributes" n=
amespace object=0A> =0A> Albert-Jan Roskam wrote:=0A> =0A>>  I find the fol=
lowing obscure (to me at least) use of type() useful exactly=0A>>  for this=
 "bag of attributes" use case:=0A>>>>>  employee =3D type("Employee", (obje=
ct,), {})=0A>>>>>  employee.name =3D "John Doe"=0A>>>>>  employee.position =
=3D "Python programmer"=0A>>>>>  employee.name, employee.position, employee=
=0A>>  ('John Doe', 'Python programmer', <class =0A> '__main__.Employee'>)=
=0A> =0A> Are you sure you know what you are doing? The above is equivalent=
 to=0A> =0A>>>>  class employee:=0A> ...=A0 =A0  name =3D "John Doe"=0A> ..=
.=A0 =A0  position =3D "Python programmer"=0A> ... =0A>>>>  employee.name, =
employee.position, employee=0A> ('John Doe', 'Python programmer', <class =
=0A> '__main__.employee'>)=0A>>>>  type(employee)=0A> <class 'type'>=0A> =
=0A> Basically you are using classes as instances. While there is no fundam=
ental =0A> difference between classes and instances in Python you'll surpri=
se readers =0A> of your code and waste some space:=0A=0AYes, I know that it=
 is equivalent, but I have always found it kind of ugly to use class() just=
 to bundle a number of items. Like you are 'announcing OOP' (not sure how t=
o put this into words), and then it's merely a simple bundle. Or maybe it's=
 just me being silly, because it's even in the Python tutorial: https://doc=
s.python.org/2/tutorial/classes.html#odds-and-ends=0A=A0=0A>>>>  import sys=
=0A>>>>  sys.getsizeof(employee)=0A> 976=0A>>>>  class Employee: pass=0A> .=
.. =0A>>>>  employee =3D Employee()=0A>>>>  employee.name =3D "John Doe"=0A=
>>>>  employee.position =3D "Python programmer"=0A>>>>  sys.getsizeof(emplo=
yee)=0A> 64=0AWow, I was not aware of that at all. So they are not equivale=
nt after all.