[texhax] enviroment/ifthen [corr'd]

[Uwe Lück]

[sorry, previous example was my first try, while I commented my second, 
which is 2009/02/10+,
now attached and copied below, wawansub.pdf as a proof attached as well; 
same posting text as before]

At 13:38 08.02.09, wawan wrote:
>I need help how to build sty in latex ( environment ) that can replace 
>squences of chars with my symbols. For example if there input chars "SU" 
>than replace with XY ( my symbols from metafont).

The macros and example in the attached wawansub.tex may be a solution. I 
just found Nicola Talbot's datatool.sty (requires substr.sty and xfor.sty) 
for replacement, while there may be other useful packages xstring.sty or under

     http://ctan.tug.org/tex-archive/help/Catalogue/bytopic.html#parsingfiles

The substitutions must be declared in the definition of \xreplacements.

There is a number of difficulties with such operations. The present 
implementation breaks when you try to embed another environment, and it 
ignores the content of curly braces. I have another version which looks 
inside braces but disables macros with arguments. This can hardly be 
improved without considerably more work.

With the present implementation the environment `substitute' must not 
contain \par.

I wonder about `my symbols from metafont' since we are just manipulating 
tokens, not glyphs as metafont produces them. Maybe you are using some rich 
encoding like Unicode, otherwise you may introduce certain commands to call 
your glyphs.

HTH -- Uwe.

________________________________________________
%% WAWANSUB.TEX 2009/02/10+ uwe.lueck[at]web.de
\documentclass[12pt]{article}

\usepackage{datatool}%% requires substr + xfor

\newcommand{\xreplacements}{%% executed on having read env
   \DTLsubstituteall{\inoutstring}{SU}{XY}%% add modifications
   % \DTLsubstituteall{\inoutstring}{<in>}{<out>}%% template
   }

\def\substitute#1\end{%
       \def\inoutstring{#1}%
       \xreplacements \inoutstring \end}

\providecommand{\disguisedpar}{\par}%% fool short arguments

\begin{document}

\begin{substitute}
ABSUOZ
\disguisedpar
abSUoz
\end{substitute}

\end{document}


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%% WAWANSUB.TEX 2009/02/10+ uwe.lueck[at]web.de
\documentclass[12pt]{article}

\usepackage{datatool}%% requires substr + xfor

\newcommand{\xreplacements}{%% executed on having read env
  \DTLsubstituteall{\inoutstring}{SU}{XY}%% add modifications
  % \DTLsubstituteall{\inoutstring}{<in>}{<out>}%% template
  }

\def\substitute#1\end{%
      \def\inoutstring{#1}%
      \xreplacements \inoutstring \end}

\providecommand{\disguisedpar}{\par}%% fool short arguments

\begin{document}

\begin{substitute}
ABSUOZ
\disguisedpar
abSUoz
\end{substitute}

\end{document}