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From: kj on 26 Mar 2010 10:49


What's the word on using "classes as namespaces"? E.g.

class _cfg(object):
spam = 1
jambon = 3
huevos = 2

breakfast = (_cfg.spam, _cfg.jambon, _cfg.huevos)


Granted, this is not the "intended use" for classes, and therefore
could be viewed as a misuse ("that's what dictionaries are for",
etc.). But other than this somewhat academic objection[*], I really
can see no problem with using classes in this way.

And yet, I've come across online murky warnings against using
classes as "pseudo-namespaces". Is there some problem that I'm
not seeing with this technique?

~K

[*] My own subjective dislike for the widespread practice of using
triple quotes to comment out code is formally similar to this one
("the 'intended use' for triple-quoting is not to comment out code",
etc.). Here I find myself on the opposite side of the purist/pragmatic
divide. Hmmm.
From: Harishankar on 26 Mar 2010 11:04
On Fri, 26 Mar 2010 14:49:02 +0000, kj wrote:

> What's the word on using "classes as namespaces"? E.g.
>
> class _cfg(object):
> spam = 1
> jambon = 3
> huevos = 2
>
> breakfast = (_cfg.spam, _cfg.jambon, _cfg.huevos)
>
>
> Granted, this is not the "intended use" for classes, and therefore could
> be viewed as a misuse ("that's what dictionaries are for", etc.). But
> other than this somewhat academic objection[*], I really can see no
> problem with using classes in this way.
>
> And yet, I've come across online murky warnings against using classes as
> "pseudo-namespaces". Is there some problem that I'm not seeing with
> this technique?
>
> ~K
>
> [*] My own subjective dislike for the widespread practice of using
> triple quotes to comment out code is formally similar to this one ("the
> 'intended use' for triple-quoting is not to comment out code", etc.).
> Here I find myself on the opposite side of the purist/pragmatic divide.
> Hmmm.

I myself am a humble beginner in many ways, but generally isn't that
(namespacing) achieved by using modules?

I don't find the need generally to assign namespace to local variables
and when there is a need for it, module level objects do the job.
From: Philip Semanchuk on 26 Mar 2010 11:08

On Mar 26, 2010, at 10:49 AM, kj wrote:

>
>
> What's the word on using "classes as namespaces"? E.g.
>
> class _cfg(object):
> spam = 1
> jambon = 3
> huevos = 2
>
> breakfast = (_cfg.spam, _cfg.jambon, _cfg.huevos)
>
>
> Granted, this is not the "intended use" for classes, and therefore
> could be viewed as a misuse ("that's what dictionaries are for",
> etc.). But other than this somewhat academic objection[*], I really
> can see no problem with using classes in this way.
>
> And yet, I've come across online murky warnings against using
> classes as "pseudo-namespaces". Is there some problem that I'm
> not seeing with this technique?

I hope it's not problematic; I use it all the time.

A few differences about the way I do it:
- I respect PEP 8 for the class name (CamelCaps)
- If the attributes are supposed to be constants, I capitalize the
attributes
- I often add NONE with a value of zero so that bool(MyClass.NONE)
will evaluate to False and everything else will be True

Here's an example from my code:

class Apodization(object):
""" Apodization constants """
# These constants are arbitrary and may change.
# However bool(NONE) is guaranteed to be False
NONE = 0
GAUSSIAN = 1
LORENTZIAN = 2



Cheers
Philip

From: Jon Clements on 26 Mar 2010 11:47
On 26 Mar, 14:49, kj <no.em...(a)please.post> wrote:
> What's the word on using "classes as namespaces"?  E.g.
>
> class _cfg(object):
>     spam = 1
>     jambon = 3
>     huevos = 2
>
> breakfast = (_cfg.spam, _cfg.jambon, _cfg.huevos)
>
> Granted, this is not the "intended use" for classes, and therefore
> could be viewed as a misuse ("that's what dictionaries are for",
> etc.).  But other than this somewhat academic objection[*], I really
> can see no problem with using classes in this way.
>
> And yet, I've come across online murky warnings against using
> classes as "pseudo-namespaces".  Is there some problem that I'm
> not seeing with this technique?
>
> ~K
>
> [*] My own subjective dislike for the widespread practice of using
> triple quotes to comment out code is formally similar to this one
> ("the 'intended use' for triple-quoting is not to comment out code",
> etc.).  Here I find myself on the opposite side of the purist/pragmatic
> divide.  Hmmm.

Given this example, I would go for the module and CONSTANT_NAMING
approach.

But yes, even in the docs. you can use a class as a C type-of struct.

I stick to the convention of a class knows what it's doing,
what it's doing it on, and a module just happens to contain those
classes.

C++ std::algorithm for instance,
makes sense it's called std, ditto algorithm and has shed loads in it,
but would I create a class called algorithm (unlikely).

I would tend to view modules as "namespace". Rightly or wrongly, just
lets you make the right design choice.

Jon.



From: Jack Diederich on 26 Mar 2010 11:49
On Fri, Mar 26, 2010 at 10:49 AM, kj <no.email(a)please.post> wrote:
>
>
> What's the word on using "classes as namespaces"?  E.g.
>
> class _cfg(object):
>    spam = 1
>    jambon = 3
>    huevos = 2
>
> breakfast = (_cfg.spam, _cfg.jambon, _cfg.huevos)

Classes as namespaces are a valid use case (I do it all the time).
Python 3 has a small cleanup that makes classes even closer to module
namespaces; namely the concept of "unbound methods" goes away. In
3.x when you get a function from a class you get the function itself
and not an unbound function.

-Jack
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