Re: character redefinition environment

[Hans Hagen <pragma@wxs.nl>]

Enzo Cordes wrote:
> Hi list,
>
> I want to assign Metapost graphics to single letters (in a newly defined 
> evironment, that take care of these assignments). The purpose is being 
> able to rapidly build huge tables containing lots of these symbols.
>
> Everything works fine if I assign these graphics to non-letters, e.g. 
> "|", but somehow it doesn't work with normal letters.
>
> Here is what I tried (with a simple Foo instead of Metapost graphics):
>
> \definesymbol[foosymbol][{\tt Foo}]
> \def\startmychars{%
> \bgroup\catcode`\|=\active\def|{\symbol[foosymbol]}}
> \def\stopmychars{\egroup}
>
> This works with | as reassigned character without any problems. But, we 
> want to have normal characters in the table, no punctuation marks, etc. 
> Does anyone know what to do to reassign a special definition for a 
> letter e.g. like uppercase B or else?
>
> I got this error:
> (/usr/local/share/texmf/tex/context/base/pdfr-ec.tex)
> ! Undefined control sequence.
> \startmychars ...up \catcode `\B=\active \defB
>                                                    {\symbol[foosymbol]}
> l.24 \startmychars
>
> which seems to indicate that B is not recognized as active character in 
> the "\defB"?
>
>   
| is already active, but not b

\bgroup
\catcode`B=\active
\def\start...

\egroup

otherwise a 'character B' and not an 'active character B' ends up in the 
definition

This may be easier:

\def\Whatever
  {\defineactivecharacter B {[oeps]}}

bla bla \start \Whatever B \stop ble bla


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