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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Thu, 28 May 2015 09:40:32 -0600
Subject: Re: should "self" be changed?
To: Python <python-list@python.org>
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On Thu, May 28, 2015 at 9:01 AM, Marko Rauhamaa <marko@pacujo.net> wrote:
> Anssi Saari <as@sci.fi>:
>
>> Do you have an example of state pattern using nested classes and
>> python? With a quick look I didn't happen to find one in any language.
>
> Here's an sampling from my mail server:

I think I would be more inclined to use enums. This has the advantages
of not creating a new set of state classes for every connection
instance and that each state is a singleton instance, allowing things
like "if self.state is SMTPConnectionState.IDLE". It could look
something like this:

class SMTPConnectionState(Enum):

    class IDLE:
        @classmethod
        def handle_command(cls, conn, cmd):
            # ...

    class SPF_HELO:
        @classmethod
        def terminate(cls, conn):
            # ...