lurc.tex

% lurc.tex
% LaTeX Utility/Template for Generic Reusable Code (LURC)
% Usage:
%
%    In main .tex file:
%
%    \InsertModule{mypath/foo}{instance-A}[key1=somevalue1,key2=somevalue2]
%
%    \InsertModule{mypath/foo}{instance-B}
%
%    \InsertModule{mypath/foo}{instance-C}[some other key=some value]
%
%
%    In mypath/foo.tex (included .tex file):
%
%    \Instance
%
%    \OneTimeOnly{
%       only once code
%       \GetKeyValue{key1}
%       \GetKeyValue{key2}
%    }
%
%    every time code
%
%    \OnlyFor{instance-A}{
%       'instance-A' code.
%    }
%
%    \OnlyFor{instance-B,instance-C}{
%       \GetKeyValue{some other key}
%       'instance-B' or 'instance-C' code
%    }

\makeatletter
\usepackage{pgfkeys}
\pgfkeys{/generic-reusable/.unknown/.code={%
        \expandafter\edef\csname gr-arg-\pgfkeyscurrentkey\endcsname{\unexpanded\expandafter{\pgfkeyscurrentvalue}}%
}}

\def\gr@markincluded#1{\global\expandafter\let\csname gr-file-#1-alreadyincluded\endcsname\empty}
\def\gr@ifincluded#1{\@ifundefined{gr-file-#1-alreadyincluded}}

\def\gr@OneTimeOnly{%
    \gr@ifincluded{\gr@filename}%
    {\@firstofone}%
    {\@gobble}%
}


\def\gr@OnlyFor#1{%
    \gr@OnlyFor@#1,\gr@nil
}

\def\gr@OnlyFor@#1,{%
    \def\gr@temp{#1}%
    \def\next{\@ifnextchar\gr@nil{\@gobbletwo}{\gr@OnlyFor@}}%
    \ifx\gr@temp\gr@requestedinstance
    \let\next\gr@OnlyFor@dobody
    \fi
    \next
}

\def\gr@GetKeyValue#1{\csname gr-arg-/generic-reusable/#1\endcsname}

\def\gr@OnlyFor@dobody#1\gr@nil#2{#2}

\def\InsertModule#1#2{%
    \@ifnextchar[{\gr@InsertModule@{#1}{#2}}{\gr@InsertModule@{#1}{#2}[]}%
}
\def\gr@InsertModule@#1#2[#3]{%
    \begingroup
    \let\OneTimeOnly\gr@OneTimeOnly
    \let\OnlyFor\gr@OnlyFor
    \let\GetKeyValue\gr@GetKeyValue
    \pgfqkeys{/generic-reusable}{#3}
    \def\gr@requestedinstance{#2}%
    \let\Instance\gr@requestedinstance
    \def\gr@filename{#1}%
    \input #1 \relax
    \endgroup
    \gr@markincluded{#1}
}
\makeatother