Hi Ken,
Incompatible change, I realise. Just trying to step back a bit and
see why we ended up here.
That was more explaining my meanderings rather than asking the question.
:-)
There are a couple of things going on here. One is, like you said,
headers tell nmh programs what to do. These are user-editable, and in
cases of things like "To: and "cc:" users are expected to edit them.
The other part is we're now using more headers as an IPC mechanism
from one set of nmh programs to another. There was always some of
this, of course - repl(1) sets the To: and/or cc: headers, but now we
are starting to make use of this for things like attach, and the
proposal for forw(1). These can also be user-editable, and I think
that's desirable. There will probably be more of them.
I think you end up in the second paragraph saying Attach, etc., fall
into the same bucket as the first's, which is how I lumped them
together. That just leaves headers that nmh doesn't read or write at
all. Bar any of those getting out by accident and we'd be half-way
there.
Here's that colon-prefix idea again. Any header without has to be in
nmh's domain. `To' is, even if the out-going email happens to have one
of the same name; nmh gets in there for the aliases, encoding, etc.
The issue tracker wants an Attach header if I'm trying to attach a file
to an existing issue. By using the colon prefix I'm stating it's a raw
mail header outside of nmh's purview and it's automatically got its own
namespace distinct from nmh's prefix-less one.
To: bughunter
From: ralph
Subject: issue 42
Attach: core
:Attach: Obtained on Arch Linux with s-nail 14.8.10-1.
As for being incompatible, Python had that `from __future__ import'
thing, Perl has `require 5.042', and .mh_profile could probably grow
something to keep *old* behaviour so new users, and old users that don't
experience breakage, get new behaviour.
--
Cheers, Ralph.
https://plus.google.com/+RalphCorderoy
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