'Flask-style' global context object

[gertvdijk]

In order to pass contextual information for the Milter-MTA session it may be elegant to provide a magic global variable like Flask's request object.

It could provide:

• all macros seen so far
• all past commands with its attributes or perhaps attributes pointing to the data directly
• instantiated logger in the session context (instead of making the logger attribute to an instantiated PurePythonMilter a global)
• a 'writable' user object to pass on state from one hook to another, like obj in Click.

This could be used like this:

from purepythonmilter import context, MailFrom, PurePythonMilter


async def on_mail_from(cmd: MailFrom) -> None:
    if context.peer_ip == ipaddress.IPv4Network("10.0.0.0/8"):
        context.logger.info(f"to={cmd.address} [{context.peer_ip} in 10.0.0.0/8]")


mymilter = PurePythonMilter(name="mymilter", hook_on_mail_from=on_mail_from)