% \iffalse
%%
%% File: afterpackage.dtx Copyright (C) 2005, 2006 by Alexander I. Rozhenko
%%
%<package>\NeedsTeXFormat{LaTeX2e}
%<package>\ProvidesPackage{afterpackage}
%<package>         [2006/01/17 v1.1 Apply Commands After Package (NCC)]
%
% \changes{v1.0}{2005/12/25}{Initial version}
% \changes{v1.1}{2006/01/17}{The package renamed to `afterpackage'}
%
%<*driver>
\let\makeindex\relax
\documentclass{ltxdoc}
\usepackage{afterpackage}
\GetFileInfo{afterpackage.sty}
\begin{document}
\title{The \textsf{afterpackage} package\thanks{This file
        has version number \fileversion, last
        revised \filedate.}}
\author{Alexander I. Rozhenko\\rozhenko@oapmg.sscc.ru}
\date{\filedate}
\maketitle
\DocInput{afterpackage.dtx}
\end{document}
%</driver>
% \fi
% The package allows specify what additional commands should be applied
% to a package after its loading. To describe the usability of
% the package, consider the task of customization of a number of
% packages. Let we need to apply some package-specific code after loading
% packages such as customization of their defaults or hooks.
% To do this, we need to load all required packages and then apply the
% related staff to them. But, sometimes loading of all required packages is
% impossible or unnecessary because packages can have options or some of
% customized packages are rarely useful.
%
% The main idea of using this package is to specify how other packages
% can be customized in such a way that their customization is applied when
% and if customized packages are loaded. All the customization is applied
% in the preamble only.
%
% \DescribeMacro\AfterPackage
% To customize a package, load the \textbf{afterpackage} package and
% insert any number of the following commands anywhere in the preamble:
% \begin{quote}
% |\AfterPackage|\marg{package name}\marg{commands}
% \end{quote}
% The command works as follows: it tests the required package to be
% already loaded; if the package is loaded, it directly applies \meta{commands};
% otherwise, it collects \meta{commands} in a special macro. The specified
% macro will be applied later when the respective package will be loaded.
% This operation is executed when the package loading finishes and all
% end-of-package hooks are applied. So, the \meta{commands} are applied
% \emph{after the end} of respective package.
%
% \StopEventually{}
%
% \section{The Implementation}
%
% \begin{macro}{\AfterPackage}
% The command tests the |\ver@|\meta{filename} command to be
% defined and considers either collect commands in a special macro
% or apply them directly.
%    \begin{macrocode}
%<*package>
\newcommand*\AfterPackage[1]{%
  \expandafter\ifx\csname ver@#1.\@pkgextension\endcsname\relax
    \@ifundefined{#1.\@pkgextension-@dd}{%
      \expandafter\let\csname#1.\@pkgextension-@dd\endcsname\@empty
      \expandafter\@onlypreamble\csname#1.\@pkgextension-@dd\endcsname
    }{}%
    \wlog{After Package Info: Collect commands for #1\on@line}%
    \def\@tempa{%
      \expandafter\g@addto@macro\csname#1.\@pkgextension-@dd\endcsname}%
  \else
    \ATP@apply@info{#1}%
    \let\@tempa\@firstofone
  \fi
  \@tempa
}
\@onlypreamble\AfterPackage
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@popfilename}
% To apply collected commands to a package, we use the |\@popfilename| hook.
% This hook is applied after loading a package. It pops a name of previous
% package or class which was active before loading a package. We save
% the original value of |\@popfilename| hook in a special macro and
% redefine it to execute the |\|\meta{filename}|-@dd| hook before pop of
% the previous filename.
%    \begin{macrocode}
\let\ATP@popfilename\@popfilename
\@onlypreamble\ATP@popfilename
\def\@popfilename{%
  \@ifundefined{\@currname.\@currext-@dd}{}{%
    \ATP@apply@info{\@currname}%
    \csname\@currname.\@currext-@dd\endcsname
    \expandafter\let\csname\@currname.\@currext-@dd\endcsname\relax
  }%
  \ATP@popfilename
}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\ATP@apply@info}
% This information message is logged when commands are applied. Its parameter
% contains a name of package which commands are customized.
%    \begin{macrocode}
\def\ATP@apply@info#1{%
  \wlog{After Package Info: Apply commands to #1\on@line}%
}
\@onlypreamble\ATP@apply@info
%</package>
%    \end{macrocode}
% \end{macro}
\endinput