Using an interface class for a constant "container" would often be handy but it
might be an inappropriate use of interface classes. FTR, I do often put
constants in an "interfaces.py" module at module scope (if there are more than
one related, sometimes in a dictionary or within a non-interface class
statement) in order to not feel I need to create some "constants.py" module.
Maybe we could just agree that doing so isn't some sort of violation of intent?
Chris Rossi wrote:
> On Fri, Apr 3, 2009 at 7:21 PM, Wichert Akkerman <wich...@wiggy.net> wrote:
>
>> Previously Chris Rossi wrote:
>>> I was wondering if the Zope collective had given any consideration to
>>> allowing constants to be defined in interfaces. To be clear, these are
>>> constant values that make up the protocol defined by the interface. Just
>> to
>>> have a concrete example, let's say we're modeling an http response:
>>>
>>> class IHttpResponse(Interface):
>>> """Models an HTTP 1.1 response.
>>> """
>>> status = Attribute("HTTP status code for this response.")
>>>
>>> It might be useful to include in our interface spec what some proper
>> values
>>> for status code might be and make them available to applications as
>> static
>>> constants on the interface class. A naive implementer might do something
>>> like this:
>>>
>>> class IHttpResponse(Interface):
>>> """Models an HTTP 1.1 response.
>>> """
>>> HTTP_OK = "200 Ok"
>>> HTTP_NOT_FOUND = "404 Not Found"
>>>
>>> status = Attribute("HTTP status code for this response.")
>> This looks like a poor man's enum. I'ld prefer to have a proper enum
>> like thing.
>>
>
> I'm sure you can think of a lot of uses of constant values where an enum
> wouldn't be appropriate. I don't know that I'd even use an enum in this
> made up example. Some use cases might be covered by an enum, sure, but
> that's not really the point here.
>
> Thanks,
> Chris
>
>
>
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