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I have a reasonable understanding now of how .dtx files work. But it's a great pain having to put a % character before every line of documentation. Also, depending on which editor you're using, it basically means: no syntax highlighting.

This problem has been noted before. But the only solutions offered were about editor settings. Plus, even if we forget about syntax highlighting, the % thing is just... inconvenient.

So I'm looking for a way to dispense with all the commenting. Basically, I'd like to delimit documentation code using guard modifiers. Something like this:

I'm going to introduce a cool new \LaTeX macro:


Cool, huh?

I think I could figure out how to do it by first extracting the documentation code into a separate file. But... do I need to? Is there a better way?

share|improve this question
I don't think it makes sense to use an editor which can not even do that. –  Stephan Lehmke Nov 23 '12 at 7:14
@StephanLehmke I'd rather put it like this: I don't think it makes sense to use a language which requires you to prefix so many lines with a comment symbol. ;-) --- Anyway, I'm using Eclipse with the TeXLipse plugin. I pretty much use Eclipse for everything, and for LaTeX it has some great features (such as synctex). This just happens not to be one of them. –  mhelvens Nov 23 '12 at 9:23
@StephanLehmke I guess you're talking about Javadoc. Two important differences: (1) it still allows you to delimit documentation with /** */ thus not requiring you to comment every line. (2) There you write down only the bare minimum of information about defined classes and methods and documentation is automatically extracted. You don't write the manual. –  mhelvens Nov 23 '12 at 9:48
@mhelvens "You don't write the manual." You don't need to do that in TeX either. The .drv usually mostly contains \DocInput{\jobname.dtx} and the whole doc is in the .dtx, but that's just convention. You can as well put the whole manual in the drv as a plain normal LaTeX document and input only the documented sources with \DocInput{\jobname.dtx}. –  Stephan Lehmke Nov 23 '12 at 9:54
By now the "doc - docstrip" workflow in the TeX community is a habit, and it seems that it won't change easily. I think you will fit right with coding in real literate-style instead of putting % at every line of documentation. Take a look at noweb. It's easy and useful. –  Jean Baldraque Nov 24 '12 at 9:52

3 Answers 3

If you look at the history of doc, then it is understandable why the current system works as it works. Initially the idea as to write a .sty file with the comments imbedded, but in a way that it would directly be processable by LaTeX. And that required putting every bit of documentation behind % signs.

Only later docstrip appeared (to strip the comments because back then processing all those unnecessary comment lines took noticable extra time). Even later the <guards> appeared and with them none-sequencial generation of target files. At that time the name of the files changed to .dtx and one could then have changed the documentation part to work without % --- but that didn't happen.

Having said this, one can with a little modification run doc in that form, e.g.,



   \frenchspacing \@vobeyspaces

\catcode`\|=\z@ \catcode`\[=\@ne \catcode`\]=\tw@
\catcode`\{=12 \catcode`\}=12

\noindent some text
more text

To the processable code out of this file one would need a docstrip install file like

\input docstrip



But it isn't fully satisfying, as the documentation guards show up in the documentation and without some serious changes to docstrip and doc I don't see a way to get rid of those:

enter image description here

perhaps it would look a little better in print if we call the guard "code" (but then * and / are in the wrong order) --- either way it is suboptimal.


If one wants to get rid of the documentation guards, one simple solution is of course to use docstrip to generate a separate documentation file as it was suggested already by the OP. To do this all one has to do is to additionally provide the line


in the .ins file and then run LaTeX on the resulting file. However, to fully utialize the features of doc, e.g., the code indexing or the code line numbering it is imortant to use the macrocode environment. As this environment uses the special syntax with % \end{macrocode} it can't be used directly at least not if one wants to avoid putting the % in. Therefore the code above defining the inlinecode environment as an alternative is essential.

Perhaps that bit of code should be added to doc to allow for this approach.

share|improve this answer
Hi! Your catcode-intensive solution is very interesting, but I find it a bit hard to follow (as I do all catcode-intensive TeX code). -<###>- And I have to say, the fact that those tags would remain visible in the documentation makes this solution... unacceptable. :-) I think the answer I just proposed myself is a bit more workable. -<###>- Nonetheless, I'll have some fun puzzling out your catcodes later. Cheers! –  mhelvens Nov 24 '12 at 19:18
@mhelvens with a bit more effort it is possible to suppress the documentation guards and leave just an empty line there. Getting rid of that line is more difficult as with \CodelineIndex the line would have a number attached. The catcode tricks are the same as used in doc.dtx, so reading its documentation should help :-). As to the visible guards: your solution shows them too, so why do you think it is more workable? –  Frank Mittelbach Nov 25 '12 at 8:42

Here is the skeleton of the dtx of a package I have written and which will appear in a few days on CTAN (the current version on CTAN does not yet have this structure of the dtx file)

% This skeleton PKG.dtx file is one way to not have everything commented
% out in the documentation part. It produces the .sty file (and also an
% .ins file) when one does latex PKG.dtx.
% It *does not* use DocInput!
% It is also possible to not produce the .sty file, and still be able to
% compile the doc, using some boolean flag, and doing an \input which
% will get only the code, the only thing is that the log file will
% complain that we have required package `' and that package `PKG' was
% used.
% Here we rather first output the .sty file, and then do a normal
% \usepackage 
% [I am of course assuming that compiling the doc for package PKG 
%  does require the use of PKG.sty]
\input docstrip.tex
\input docstrip.tex
This is a another file which can be produced by the latex run
% \OnlyDescription
\usepackage{PKG} % <- often needed to produce its own documentation!
I am the best packaging package.



% \catcode`\<=0 \catcode`\>=11 \catcode`\*=11 \catcode`\/=11 
% \let</none>\relax
% \def<*package>{\catcode`\<=12 \catcode`\>=12 \catcode`\*=12 \catcode`\/=12}
%    \begin{macrocode}
 [2012/11/24 v1.04 easy packaging (jfB)]
%    \end{macrocode}
% Let us point out the importance of this piece of code with 31
% \cs{expandafter}'s
%    \begin{macrocode}
%    \end{macrocode}
% \MakePercentComment
 {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
  Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
  Digits        \0\1\2\3\4\5\6\7\8\9
  Exclamation   \!     Double quote  \"     Hash (number) \#
  Dollar        \$     Percent       \%     Ampersand     \&
  Acute accent  \'     Left paren    \(     Right paren   \)
  Asterisk      \*     Plus          \+     Comma         \,
  Minus         \-     Point         \.     Solidus       \/
  Colon         \:     Semicolon     \;     Less than     \<
  Equals        \=     Greater than  \>     Question mark \?
  Commercial at \@     Left bracket  \[     Backslash     \\
  Right bracket \]     Circumflex    \^     Underscore    \_
  Grave accent  \`     Left brace    \{     Vertical bar  \|
  Right brace   \}     Tilde         \~}


%% End of file

The actual situation in my dtx file is more complicated, I simplified things here to get that skeleton. I agree that having all those % is indeed a problem, although with emacs there is a mode which does the LaTeX syntax highlighting nevertheless. So I was also interested in finding a way not to have all those %'s.

Oups, I forgot to say that the ins stuff is purely optional. It is only to produce an .ins file, but it is not used, as the .sty file itself is directly output.

share|improve this answer
Ah, I see. The trick here, then, is to manually call \MakePercentIgnore before starting the 'implementation' section. So you have most of the documentation without the %s, but you still need them for that last section. Correct? Interesting solution. –  mhelvens Nov 24 '12 at 21:47
@mhelvens: Yes, the commenting of the source code is still done with the %, in the standard manner. But the user manual can be entirely written without the %. The important thing is when I realized I should forget entirely about using \DocInput!! –  jfbu Nov 24 '12 at 21:50
Yes, I did the same thing in my own solution, but took it a bit further. I'm not commenting out lines of code anywhere. Whether or not that's better can be debated. But I suppose you could say that my solution is more purely literate programming, as the program is 'submissive' to the documentation. That is to say: it is merely part of the story. In your solution, the documentation still takes a back seat, so to say. But I suppose this is bordering on the philosophical. –  mhelvens Nov 24 '12 at 22:40
@mhelvens: interesting! I didn't think about going as far as you did, simply because Emacs handles beautifully the % at the start of lines, it is just as if they were not there for syntax highlighting and automatized filling. However in the user manual part I may have to copy paste to plain .tex file and then the % are slightly a nuisance. So I was mainly keen on getting rid of them in this user manual part, before the commented source code. –  jfbu Nov 29 '12 at 7:26
@mhelvens: and of course no line of code is commented out in the implementation part, only the lines of commenting are commented out, in the standard macrocode manner. –  jfbu Nov 29 '12 at 7:27
up vote 1 down vote accepted

Ok, so maybe it's not possible to do this elegantly using the 'standard' way of running the .dtx file through LaTeX to get the docs. But I have an alternative solution here which seems just as nice.

With this setup, there is only one file (the '.ins file' is included). You run it through LaTeX and it generates package.sty and package.tex. To get the actual documentation you still need to run package.tex itself through LaTeX. (A sacrifice I am willing to make.)

Here is a minimal working example (and a reasonable skeleton for anyone wanting to do the same):

%%  Copyright, license, etc... %

%% \CheckSum{3}
%% \CharacterTable
%%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
%%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
%%   Digits        \0\1\2\3\4\5\6\7\8\9
%%   Exclamation   \!     Double quote  \"     Hash (number) \#
%%   Dollar        \$     Percent       \%     Ampersand     \&
%%   Acute accent  \'     Left paren    \(     Right paren   \)
%%   Asterisk      \*     Plus          \+     Comma         \,
%%   Minus         \-     Point         \.     Solidus       \/
%%   Colon         \:     Semicolon     \;     Less than     \<
%%   Equals        \=     Greater than  \>     Question mark \?
%%   Commercial at \@     Left bracket  \[     Backslash     \\
%%   Right bracket \]     Circumflex    \^     Underscore    \_
%%   Grave accent  \`     Left brace    \{     Vertical bar  \|
%%   Right brace   \}     Tilde         \~}

%<*driver>                                                                     %

\input docstrip.tex





\Msg{*                                                           *}
\Msg{* To finish the installation you have to move the following *}
\Msg{* file into a directory searched by TeX:                    *}
\Msg{*                                                           *}
\Msg{*     package.sty                                           *}
\Msg{*                                                           *}
\Msg{* To produce the documentation run the following file       *}
\Msg{* through LaTeX:                                            *}
\Msg{*                                                           *}
\Msg{*     package.tex                                           *}
\Msg{*                                                           *}
\Msg{* Happy TeXing!                                             *}
\Msg{*                                                           *}


%</driver>                                                                     %
%<*d>                                                                          %





\changes{v0.0.1}{2012/11/16}{initial version}
\changes{v0.0.2}{2012/11/24}{put the package into a .dtx file}



\title{The \textsf{package} package\thanks{This document
  corresponds to \textsf{package}~\fileversion, dated \filedate.}}
\author{Author Name \\ \texttt{author@mail.com}}

\begin{document}                                                               %


\section{Introduction}                                                         %

Put text here.

\section{Usage}                                                                %

Put text here.

This macro does nothing.

This environment does nothing.

\section{Implementation}\StopEventually{}                                      %

The following piece of code contains the package meta-info:


        [2012/11/24 v0.0.2 description of the 'package' package]


    This is a dummy macro.

%</d>   %%%%%%%%%%%%%%%%%%%%%%%


%<*d>   %%%%%%%%%%%%%%%%%%%%%%%

    This is a dummy environment.

%</d>   %%%%%%%%%%%%%%%%%%%%%%%


%<*d>   %%%%%%%%%%%%%%%%%%%%%%%

    Some more information here... Very useful stuff.

\Finale\end{document}                                                          %

Some remarks:

  • The '.ins' part is terminated with \endbatchfile, so everything that comes afterwards is ignored on the first run. It is also delimited with %<*driver>, so it is itself ignored on subsequent runs.
  • The copyright / licensing / file integrity stuff is automatically included in every generated file.
  • In pure literate programming style, I made the package code 'submissive' to the documentation by my use of indentation. But you can choose to indent differently.

The only thing I couldn't get working was the macrocode environment. Perhaps it depends on the standard docstrip setup somehow? It was too hard to decipher its definition. So I'm using verbatim here to typeset the package code, but any code-typesetting technique (such as listings) would work.

Any feedback would be appreciated!

Edit: The previous version didn't work because I indented the guards. The %<*bla> code cannot have whitespace to its left. :-( Oh well. I also just noticed that the verbatim environment keeps all whitespace. (But there are solutions to that.)

share|improve this answer
One of the tasks that doc does is to properly index all of the code lines. If you do not use macrocode but verbatim that is not happening! Besides your solution has the same "defect" as mine, it will show the documentation guards. So I don't see what you gain, my solution does run directly off the .dtx and produces output comparable to yours, or not?. Speaking of decipering the doc code: you are reading the documented version or just the style file? I thought the former is fairly well documented. –  Frank Mittelbach Nov 25 '12 at 8:40
@FrankMittelbach No, I'm getting clean code on my end. Have you actually run my code through LaTeX? ### Very good point about indexing the code. I'll take a look at the documented doc code. –  mhelvens Nov 25 '12 at 8:42
I sure have. your file package.tex contains the guards and so they show up in the documentation. Just like they show up in my version in the documentation. The code is clean, yes, but so is mine if you run a .ins file to extract the code. Did you try it? –  Frank Mittelbach Nov 25 '12 at 8:48
@FrankMittelbach You're right! I don't know how that happened. I had a version yesterday which definitely didn't show the guards, and I thought I copied it exactly. I'm going to figure this out. Thanks for the pointer. –  mhelvens Nov 25 '12 at 9:07
@FrankMittelbach It was because I indented the guards. Apparently you can't (too bad). –  mhelvens Nov 25 '12 at 9:18

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