[Email-SIG] API thoughts

[Steffen Daode Nurpmeso]

Barry Warsaw wrote:
> I personally like this part of the API, and I think it's held up well under
> years of use.

:-) 
msg[f] is indeed and really an elegant and understand-at-a-glance 
way to access headers. 
(Possible restriction: it would be graceful if it would return and 
take a list.)

> Well, replace one header retaining original order is a bit difficult, but I've
> rarely had to do that.
[...]
> I think it could too, by adding an index argument to .replace_header(),
> and using .get_all() to get an ordered list of the headers of interest.

... and give me a way to also delete just one body of a field and 
i'll be lucky. 
Maybe simply 'Message._headers = {normalized_field = [bodies]}'? 
But, why not .delete_all_of(0, 2, 5), realized by a walk in equal 
spirit to .get_all().

(My thought was that a new Proxy class can be added very easily, 
requiring only one new method in Message and 
without affecting the remaining interface, 
whatever status David's local EMAIL 6 branch is currently in and 
whatever approach he will have chosen in the end.

Anyway, and unless i missed something, this is the current way:

    def _bewitch_msg(self):
        """Handle Python 3.2.0/3.3a0 issue 11401 email/message.py error"""
        if sys.hexversion > 0x030300A1 or sys.hexversion > 0x030200F1:
            return

        for f in self._msg:
            had_repl = False
            new_ab = []
            ab = self._msg.get_all(f)
            for b in ab:
                if not len(b):
                    had_repl = True
                    b = ' '
                new_ab.append(b)
            if had_repl:
                del self._msg[f]
                for b in new_ab:
                    self._msg[f] = b

At best the very same could be achieved (faster and with smaller 
memory footprint):

        for p in self._msg.proxy_iter():
            for (idx, body) in p:
                if not len(body):
                    p[idx] = ' '
)