Plain TeX macros with \obeylines and no delimiters.

Question

How can I define a macro, say \address, so that I can use it like this:

\address
27/7 Montague Street
Edinburgh

and it would put the lines following it into another macro, say \addrinfo ? What I'm ultimately trying to do, is modify Knuth's letter macros so that I can specify the address once in the letter, and then produce an address in a different font. Currently I've got

\newbox\theiraddressbox
\def\address{\beginlinemode%                                                               
 \global\setbox\theiraddressbox=\vtop\bgroup\raggedright
  \hsize=\longindentation \everypar{\hangindent1cm}
  \def\endmode{\egroup\endgroup\bigskip\copy\theiraddressbox}}

but this means the address label is set in the same font.

Answer 1

What you can do is to put each line into a separate definition as part of the definition of \address. In Knuth's letter format, he puts the first line of the address in the definition of \addressee.

The idea is to do this for the whole address. Then you'll have the definitions of \ToName, \ToStreet etc to use afterwards in any way you like.

A minimal example to illustrate the idea is as follows:

\def\beginlinemode{\endmode\begingroup\obeylines\def\endmode{\par\endgroup}}
\let\endmode=\par
\def\address{\beginlinemode\getToAddress}

% Populates the \To* definitions.
{\obeylines\gdef\getToAddress#1
  #2
  #3
  #4
  {\gdef\ToName{#2\unskip}%
   \gdef\ToStreet{#3\unskip}%
   \gdef\ToCity{#4\unskip}%
   \def\beginletter{\endgroup\bigskip}}}


\address
Some Name
27/7 Montague Street
Edinburgh


\beginletter

And now you can use the different fields as you wish. For example:

\bigskip
\moveright2cm\vbox{\hbox{\ToName}\hbox{\ToStreet}\hbox{\ToCity}}
\bigskip

This letter is addressed to {\bf \ToName}.

\bye

You can also have a \FromAddress macro similar to \address, but whose ending markup is \address instead of \beginletter. So you'd start your letter like:

\FromAddress
My Name
My Street
My City

\address
To Name
To Street
To City

\beginletter

etc

Answer 2

In effect, your \address macro is not undelimited: Somehow, the \endmode macro has to get called afterwards. In Knuth's letter macros, this job is done by the \body macro. So, what you can do is delimit the \address macro like this:

\def\address{\beginlinemode\getaddress}
\def\getaddress#1\body{\gdef\theaddress{#1}\body}

Then the macro \theaddress will contain the unformatted address. Hope you can work out the missing details.