Re: letter: backaddress

[Wolfgang Schuster <schuster.wolfgang@googlemail.com>]

Am 27.03.10 17:56, schrieb Wolfgang Werners-Lucchini:
> I do not understand the the main principle.
>    
You're mixing different things.
> What is the difference between
>
> \setupletterstyle[option][backaddress=yes]
>    
In t-letter.tex you can fint this:

\startsetups[\v!letter:\v!layer]

   \doif\@@@@lsoptionmarking    
\v!yes{\directsetup{\v!letter:\v!place:\v!foldmark   }}
   
\doif\@@@@lsoptionbackaddress\v!yes{\directsetup{\v!letter:\v!place:\v!backaddress}}
   \doif\@@@@lsoptionaddress    
\v!yes{\directsetup{\v!letter:\v!place:\v!address    }}
   \doif\@@@@lsoptionreference  
\v!yes{\directsetup{\v!letter:\v!place:\v!reference  }}
   \doif\@@@@lsoptionlocation   
\v!yes{\directsetup{\v!letter:\v!place:\v!location   }}
   \doif\@@@@lsoptionlettermain 
\v!yes{\directsetup{\v!letter:\v!place:\v!lettermain }}
   \doif\@@@@lsoptionletternext 
\v!yes{\directsetup{\v!letter:\v!place:\v!letternext }}

\stopsetups

With \setupletterstyle[<element>=yes|no] you can show or hide elements
(like the foldmarks or the backaddress) in the output.
> \setupletterstyle[backaddress][alternative=yes]
> 	
> In 'default.nli' I found
>
> \defineletterelement[\v!backaddress][\v!auto]
>    {\doifelselettervalue\c!backaddress
>       {\lettervalue\c!backaddress}
>       {\lettervalue\c!fromname
>        \doiflettervalue\c!fromaddress\\
>        \lettervalue\c!fromaddress}}
>
> what I interpret in the following way:
>
> If 'backaddress'=auto
>    If exist a constant 'backaddress'
>      use it
>    else
>      compose one from 'fromname' and 'fromaddress'
>    
The constant needs a content, if there is no content for 'backadress'
the field is filled with 'fromname' and 'fromaddress'.

\defineletterelements creates a macro, where the first argument is
the name of the elements and the second a name for the alternative,
e.g. \defineletterelement[<element>][<alternative>]{definition}

You can use the created element with 
\setupletterstyle[<element>][alternative=<alterntive>],
in your case \setupletterstyle[backaddress][alternative=auto]

When you don't like this mechanism you can use the internal
element setups itself with

\startsetups letter:backaddress
...
\stopsetups

Wolfgang

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