Welcome!
Doxygen is a free1)
tool that extracts specific source code comments and analyzes the declarations of your
code, to create a comprehensive online documentation, similar to the Tools/Build
Comment web pages command in Visual Studio.NET. If you want the same for VC++6, or
maybe some more flexibility and options, this article is for you.
Once setup, Doxygen can generate create a HTML documentation of your code at one click.
It's still you who has to write the documentation, and if you want quality, it's still
your job. However, an automated system can do a lot of vanilla tasks, and setting up
the one-click documentation process is the first step to take: if you see the results
of your effort immediately, it will soon feel natural to add the right type of comments.
1) Doxygen is written by Dimitri van Heesch, and
released under the GNU
public license (GPL). The documentation created by doxygen is not affected by the GPL.
See the Doxygen
Homepage for more information.
What do I have for you today?
- Setting it up - a quick step-by-step guide to setting up and
integrating doxygen with VC++ 6 - Documenting Basics - hot to make doxygen understand your comments.
- Rationale - why to use doxygen? (skip if you are already
convinced) - Working with Doxygen - discusses the sample setup from 1), and
provides an introduction to the most important doxygen features. - Additional Resources (not much right now)
So let's jump right in!
Setting it up
This will show you how to integrate doxygen in VC++ 6, and set it up for one of your
projects. I assume you already have a project you want to try doxygen on (if not, any C++
file will do). The whole process will take about 5 minutes (depends on your download
speed).
Note: this setup does not work very well if you have a workspace with multiple projects
in sub folders. See below for more.
| doxygen binaries [^] | 1. Download the Win32 binaries and install them I'll assume in the following you installed doxygen in c:\program files\doxygen. |
| doxygen tools | 2. Download and extract my doxygen tools and keep them safe and warm in a folder of your choice. They contain all the individual files mentioned in this article |
| Add VC++ Tool: "doxygen" | Add a new custom tool, called "DoxyGen", with the following parameters:
|
| Add VC++ Tool: "view results" | add another tool, to view the results new "View DoxyDoc" tool, to view the results:
|
| Add to project |
|
| You're done! Try! | choose Tools/doxygen from the menu, and watch the magic happen (doxygen will log it's progress and complaints to the output window). Choose Tools/View results to explore the documentation. The |
Documenting Basics
Unless you already use some comment style that doxygen understands, the documentation
is pretty much meaningless. So what can you do?
1. Add a comment block before classes and structures, using ///
Just use /// for the comment block:
/// SNAPINFO holds the data for calculating a modified window rect. Since it
/// only works on coordinate rects, it can be used without any actual Windows.
struct SNAPINFO
{
// ...
}
2. Add a brief comment to to class member declarations
Use /// if you put a single line before the member. Use ///< if you put the comment
behind the member
struct SNAPINFO
{
/// Init, using a pre-change and a post-change rectangle
void Init(RECT const & oldRect, RECT const & newRect, DWORD snapwidth);
void SnapHLine(int y); ///< Snap to a horizontal line
}
3. Add a detailed description to the method implementation
as with classes, use a /// - comment block
/// Initializes the structure with an old an a new rectangle.
/// use this method if the window is about to be moved or resized (e.g. in
/// WM_SIZING or WM_MOVING handler)
void Init(RECT const & oldRect, RECT const & newRect, DWORD snapwidth)
{
// ...
}
I prepared an example for a small class of another article, which had virtually no
documentable comments.
| original code [^] | documentation [^] | |
| brief comments added [^] | documentation [^] | 13 new lines 2 with comment style modified |
| method desciptions added [^] | documentation [^] | 14 additional lines (with ehavy copy&paste) |
| without EXTRACT_ALL option | documentation [^] |
Note: as soon as you have added a basic doxy-comment to the important
classes, you should turn off the EXTRACT_ALL option (as done in default2.doxygen).
Undocumented classes are excluded, This will very much reduce the clutter in the
detailed documentaiton section.
Rationale
When working with VS.NET I noticed that the Tools/Build comment web pages is a
great motivaiton for me to add useful function and class comments to my sources. Having a
large VC6 code base to maintain, which, for a huge part, already has the comments, but no
tool to extract, I was pointed to doxygen, and got it running in relatively short time.
So, maybe you're not convinced, so here are three questions for you, with some
(suggestive) answers.
First Question: Do You need a software documentation?
Reasons are many:
- your company requires some documentation
- you're not convinced you understand all of your code after not looking at it for half a
year - your co-workers pester you with ""how do I do this" questions about your
tool library. - you plan to retire or move on, and don't want your precious code to end up in the
garbage, pillaged and rewritten by someone you don't even know, just because he doesn't
take the time for it. - you feel better
Of course you can live without for an amazinghly long time, especially when you work on
your own, or in a very small team. However, once a project grows beyond a certain size,
you'll start to want some formal documentation. And the earlier you start, the
better it is. Having set up a tool ready to be used, waiting for you tears down the
biggest obstacle - getting started.
Second Question: Why use an automated system?
- Documentation is up-to-date
You are much more likely to change a comment atop of the function you fiddle with, than
fire up MS Word, look for the function documentation, and change it there.
- Reuse of your own comments
Assuming you already discovered the virtue of commenting your own code, the market value
of your comments just doubled.
- automatic formatting, and crosslinking
with a few simple markups, you get documentation that looks professional and consistent,
and creates links to the description of all important entities. Forget about struggling
with MS Word.
- In-code comments carry important meta information
Not all important information is available from the actual "raw" source code.
Interface contracts, pre- and post-conditions, side effects, meaning of special
parameters, etc. need to be known to anyone who is to maintain the code - be it yourself
or someone else. A formal style for these comments, in conjucntion with a parser (like
doxygen's XML export) can make this informaiton available in customized format for various
recipients: be it project management, testers, and the like.
Third Question: Why doxygen?
- It's free - so it's perfect for
- cheapskates
- sneaking it into the development process, in case noone cares about at your place
- evaluating if and how an automated documentation system can help you
- find out what features you expect when you shop for something better
- OpenSource with installer
It's fairly comfortable to use (see also "Using Doxygen" below), so having the
source code available comes as an added bonus.
- Configurable
With a basic style sheet, and twiddling the options in the doxygen configuration file
(easy by using the doxywizard), you can customize many aspects ofthe documentation to your
needs.
Documenting an existing code base
Maybe you have a large project, where you wished someone would have had the patience to
add extractable comments. Yet, the idea of walking through documenting 10.000 lines of
code, and documenting them makes you shudder. Here are some suggestions:
- Set up doxygen for the project. It's five minutes, and without nothing will happen
- Document everything you write anew.
- Touch up the code you work on. If you fiddle around with some function anyway, it's
easiest to add some extra comments. Often it is just copying around / adjusting some
existing comments to look a bit nicer. - Spend 5 minutes before lunch break on adding comments. Or: comment one function for each
visit to the CodeProject lounge
Soon you will feel more "fluid" in documenting your code, and adding brief
comments to an existing class is a matter of minutes. If the benefits of having the
documentation kick in, you are encouraged to carry on.
Working with Doxygen
The setup used above is quite generic. You can generate a default configuration file
using doxygen -g, or by using the doxywizard. the latter makes
playing around with various options fairly easy.
For each docmentable entity, doxygen looks for a brief comment, and a detailed
description. The brief comment is addedto various overviews (liek the class member
listing).
Comment Style
Doxygen recognizes other comment formats as well - I chose the above for both personal
taste and compliance with those understood in .NET. For a comprehensive list, see Commenting the
code in the doxygen
documentation.
Other doxygen Options:
For the default.doxygen, I changed some of default options, notably:
- EXTRACT_ALL enabled: so some generation is created even for
"undocumented" code
I'd strongly recommend for existing projects to first add some documentation to the most
important class declarations and methods, and then turn off the EXTRACT_ALL
option. This makes the documentation less cluttered, and gives you even more more
inducement to document what isn't
- JAVADOC_AUTOBRIEF: this allows to have both the brief comment
anddetailed description in one block (despite it's name, it works for C++ sources, too)
The first line of a comment block (up to the first period) is used as brief description.
- WARN_FORMAT set to $file($line): $text
- so you can double-click doxygen warning messages in the output window to jump to the
relevant source line
- INPUT : I added a single "." as INPUT
directory, and checked the RECURSIVE option. this will scan the
working directory (set to the workspace folder in the VC++ custom tool), and added a
reasonable list of files to scan (.IDL files work very well, too!). You could specify
exclude patterns, too (e.g. *_i.c and *_p.c
for ATL projects to exclude some of the internal guts from documentation)
- Source browser: I enabled the SOURCE_BROWSER option, so the sources are included and
crosslinked (doxygen removes all doxygen-style comments, but leaves all other comments
in).
- I disabled the REFERENCED_BY_RELATION and REFERENCES_RELATION
options. They can be valuable if you want to explore the interdependencies of complex
code, but for the things I'm working on it's just clutter.
- for the HTML_OUTPUT I set doxydoc as
directory (it will be created under the working directory)
Tip: When specifying dorectory names in doxygen config files -- if it contains spaces, put it into quotes (this is a good idea for other options as
well) - do not end them with a backslash - doxygen uses it to spread argument
lists over multiple lines - doxygen will try to create non-existing output directories, but cannot generate multiple
levels.
- if it contains spaces, put it into quotes (this is a good idea for other options as
- GENERATE_TREEVIEW : While I left it disabled for the default,
you shoud try it!
Documentation Markup:
Doxygen allows for simple markup tags in the comments (I used some in the sample
documentation) they start with either a backslash, or an @. The most important I listed
here:
| \param name descripiton | Intended for documenting function parameters. see the full sample source and documentation for how it looks like. |
| \return description | desribe what a function returns |
| \b \c \e | set the next word to bold, italic, or courier, respectively. e.g. /// You can make things \b bold, \e italic, or set them in \c courier results in You can make things bold, italic, or set them in courier. |
| \code \endcode | starts and ends a section of code, respectively. (it will be formatted nicely) |
| \n | force a newline |
| \internal | starts a paragraph with "internal information" (such as implementaiton details). The paragraph will be included only if the INTERNAL_DOCS option is enabled. |
| \mainpage | Indictaes that the following section should appear on the main page. it's a good place to introduce your most important classes, etc. (entities will be crosslinked) |
| \par \par Title | Starts a new paragraph (optionally with a paragraph title), works also inside other paragraphs (such as \param) |
| Lists | Doxygen automatically creates a list if multiple lines start with a dash at the same position. Numbered lists can be created by starting the line with a dach and a hash (-#). See the doxygen documentation for more. |
| More... (doxygen documentation) | Doxygen supports many more tags, many of them allowing for further markup, or are intended for working in conjucntion with the XML export. (e.g. you can makr the specificaiton of pre- and post-conditions, bugs, test cases, todo's, etc.) |
| HTML (doxygen documentation) | Doxygen also supports HTML tags, which get converted to other outputs mroe or less correctly. |
Additional Resources
Macros:
It's convenient to set up some auto-text bound to hotkeys for writing documentation. I
just use some macros, and assign shortcuts to it manually: Setup is a bit of a hassle, but
it's worth it:
- copy doxygen.dsm
into the [DevStudo]\Common\MSDev98\Macros folder - Start VC++, choose Tools/Customize...
- on the "Add ins and macros" tab, enable the doxygen.dsm macro file
- On the Keyboard tab, choose "Macros" under Category, and assign your preferred
shortcuts to the commands
Here's a list of the macros I use:
| Macro Name | Description | my shortcut |
| DoxyComment | three slashes and a space (I use it rarely , but it's there) | Ctrl-# (german keyboard..) |
| DoxyCommentNL | newline + '/// ' - perfect for writing block comments (just press Ctrl-Enter instead of just Enter) | Ctrl-Enter |
| DoxyCommentPrev | '///< ' : for brief comments behind the declaration | Ctrl-Shift-# |
| DoxyDocFunction | a simple header to comment a function | Ctrl-Shift-F |
Style Sheets:
You can generate a default doxygen style sheet, HTML header and footer by calling
doxygen -w html <header_name> <footer_name> <stylesheet_name>
I did this for you already: doxygen_header.html,
doxygen_footer.html,
and doxygen_default.css.
The default style sheet is a good starting point for your own.
DoxyWizard:
In closing, just a little tip: Together with doxygen comes DoxyWizard, a UI tool to
edit the configuration files. It's ok to use, the "quick help" gives a short
explanaiton of each option. As I named all my config files .doxygen,
I associated this extension with doxywizard, so life got much easier, and playing around
with the options is much more fun.
Other Systems:
If you have experience with other documentation systems, feel free to (dis-)recommend
them in the comments section - as long as you don't make it an advertisement, and stay
within what's considered good taste on CP.
Ref : http://www.codeproject.com/KB/tips/doxysetup.aspx
No comments:
Post a Comment