Can I convert a dtx file to tex file

Question

I know dtx file is literate programming style file. I also know that I can compile it with pdflatex to generate pdf file. But I wonder could I just extract the tex code to a independent file? I think I can learn some thing from the tex source.

Answer 1

A DTX file is already a LaTeX file (sometimes called .tex file), however it uses some special things. It contains the description as comment lines and the package source code. It contains a "driver" preamble and body which includes the same file again with the % comment character disabled, so that the originally commented-out part is now read as normal LaTeX code. You can have a look at the description part simply by looking at the file, if you don't mind the comment style.

If you want to turn it into a normal LaTeX file, simply remove the comment % characters from the code and completely delete the implementation part. Then I would change the "driver" head part to not include the file but place the description body directly there by removing the \DocInput{..} and moving the \end{document} to the end of the file.

So basically change:

% \iffalse
%<*driver>
\documentclass{ltxdoc}
\usepackage{mypkg}
\EnableCrossrefs
\CodelineIndex
\RecordChanges
\begin{document}
  \DocInput{mypkg.dtx}
  \PrintChanges
  \PrintIndex
\end{document}
%</driver>
%\fi
% Description
% ...
% Implementation
%   \begin{macrocode}
%<*package>
code
%</package>
%   \end{macrocode}
% ...
% END of file

to:

\documentclass{ltxdoc}
\usepackage{mypkg}
\begin{document}
  Description
  ...
\end{document}

You can and should still use the ltxdoc class.

Answer 2

Usually package.dtx is accompanied by package.ins and running LaTeX on the latter extracts the code (commonly in package.sty, but in some cases other files are created).

In some cases package.ins is not present; in these cases,

pdflatex package.dtx

will typeset the documentation and extract the code; however sometimes it's necessary to run

tex package.dtx

for extracting the code (it's the case with H. Oberdiek's packages).

However, the purpose of package.dtx is not only to provide the package documentation, but also comments to the code.

If running LaTeX on package.dtx doesn't typeset the commented code, you can write a file ltxdoc.cfg in the working directory containing the line

\AlsoImplementation

and run LaTeX on package.dtx again.