[Nmh-workers] More mh-format stuff

[Ken Hornstein]

Sigh.  This just keeps getting more and more addictive; every time I try
to something with the format language, I can't help thinking, "Man, this
would be easier with a REAL embedded language".  But that would take
too long, so I'm stuck nibbling around at the edge.

Anyway ... when working on the new From: line stuff, I realized it might
be useful to have %(putaddr) format the From: header.  But as we have it
now, that's not possible.

Why?  Well, what we have now is the From: header would look something
like this:

From: %<(profile Local-Mailbox)%(putstr)%|%(myname) <%(me)@%(myhost)>%>

But this doesn't work if we want to use %(putaddr).  The reason for
this is because %(putaddr) wants to work on the "str" register, but
because we are building up the user's email address with primitives
we don't have a way to build up the "str" register; you can set a single
part of it with any one of those functions, but there's no "append"
operation.  %(lit) does not do any escapes; it can only take
a literal string.

The solutions that come to mind are this:

- Simply ignore the problem and don't use %(putaddr)
- Create some functions to append text to the "str" register.  We might
  need two of them: one to append literal strings and one that would
  take expressions.

Thoughts?

--Ken