# GTK-Doc Manual

1.18.1

User manual for developers with instructions of GTK-Doc usage.

Chris Lyttle

                chris@wilddev.net

Dan Mueth

                d-mueth@uchicago.edu

Stefan Kost

                ensonic@users.sf.net

GTK-Doc project

    gtk-doc-list@gnome.org

2000, 2005 Dan Mueth and Chris Lyttle
2007-2011 Stefan Sauer (Kost)

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is &FDLlink;.

Many of the names used by companies to distinguish their products and services are claimed as trademarks. Where those names appear in any GNOME documentation, and those trademarks are made aware to the members of the GNOME Documentation Project, the names have been printed in caps or initial caps.

1.19
05 Jun 2013
ss bug fixes
1.18
14 Sep 2011
ss bug fixes, speedups, markdown support
1.17
26 Feb 2011
sk urgent bug fix update
1.16
14 Jan 2011
sk bugfixes, layout improvements
1.15
21 May 2010
sk bug and regression fixes
1.14
28 March 2010
sk bugfixes and performance improvements
1.13
18 December 2009
sk broken tarball update
1.12
18 December 2009
sk new tool features and bugfixes
1.11
16 November 2008
mal GNOME doc-utils migration

## Introduction

This chapter introduces GTK-Doc and gives an overview of what it is and how it is used.

### What is GTK-Doc?

GTK-Doc is used to document C code. It is typically used to document the public API of libraries, such as the GTK+ and GNOME libraries. But it can also be used to document application code.

### How Does GTK-Doc Work?

GTK-Doc works by using documentation of functions placed inside the source files in specially-formatted comment blocks, or documentation added to the template files which GTK-Doc uses (though note that GTK-Doc will only document functions that are declared in header files; it won't produce output for static functions).

GTK-Doc consists of a number of perl scripts, each performing a different step in the process.

There are 5 main steps in the process:

1. Writing the documentation. The author fills in the source files with the documentation for each function, macro, union etc. (In the past information was entered in generated template files, which is not recommended anymore).

2. Gathering information about the code. gtkdoc-scan scans the header files of the code looking for declarations of functions, macros, enums, structs, and unions. It creates the file `<module>-decl-list.txt` containing a list of the declarations, placing them into sections according to which header file they are in. On the first run this file is copied to `<module>-sections.txt`. The author can rearrange the sections, and the order of the declarations within them, to produce the final desired order. The second file it generates is `<module>-decl.txt`. This file contains the full declarations found by the scanner. If for some reason one would like some symbols to show up in the docs, where the full declaration cannot be found by the scanner or the declaration should appear differently, one can place entities similar to the ones in `<module>-decl.txt` into `<module>-overrides.txt`.

   gtkdoc-scangobj can also be used to dynamically query a library about any GObject subclasses it exports. It saves information about each object's position in the class hierarchy and about any GObject properties and signals it provides.

   gtkdoc-scanobj should not be used anymore. It was needed in the past when GObject was still GtkObject inside gtk+.

3. Generating the "template" files. gtkdoc-mktmpl creates a number of files in the `tmpl/` subdirectory, using the information gathered in the first step. (Note that this can be run repeatedly. It will try to ensure that no documentation is ever lost.)

   Since GTK-Doc 1.9 the templates can be avoided. We encourage people to keep documentation in the code. gtkdocize supports now a `--flavour no-tmpl` option that chooses a makefile that skips tmpl usage totally. If you have never changed file in tmpl by hand, please remove the directory (e.g. from version control system).

4. Generating the SGML/XML and HTML/PDF. gtkdoc-mkdb turns the template files into SGML or XML files in the `sgml/` or `xml/` subdirectory. If the source code contains documentation on functions, using the special comment blocks, it gets merged in here. If there are no tmpl files used it only reads docs from sources and introspection data. We recommend to use Docbook XML.

   gtkdoc-mkhtml turns the SGML/XML files into HTML files in the `html/` subdirectory. Likewise gtkdoc-mkpdf turns the SGML/XML files into a PDF document called `<package>.pdf`.

   Files in `sgml/` or `xml/` and `html/` directories are always overwritten. One should never edit them directly.

5. Fixing up cross-references between documents. After installing the HTML files, gtkdoc-fixxref can be run to fix up any cross-references between separate documents. For example, the GTK+ documentation contains many cross-references to types documented in the GLib manual. When creating the source tarball for distribution, gtkdoc-rebase turns all external links into web-links. When installing distributed (pregenerated) docs the same application will try to turn links back to local links (where those docs are installed).

### Getting GTK-Doc

#### Requirements

Perl v5 - the main scripts are in Perl.

DocBook DTD v3.0 - This is the DocBook SGML DTD. http://www.ora.com/davenport

Jade v1.1 - This is a DSSSL processor for converting SGML to various formats. http://www.jclark.com/jade

Modular DocBook Stylesheets This is the DSSSL code to convert DocBook to HTML (and a few other formats). It's used together with jade. I've customized the DSSSL code slightly, in gtk-doc.dsl, to colour the program code listings/declarations, and to support global cross-reference indices in the generated HTML. http://nwalsh.com/docbook/dsssl

docbook-to-man - if you want to create man pages from the DocBook. I've customized the 'translation spec' slightly, to capitalise section headings and add the 'GTK Library' title at the top of the pages and the revision date at the bottom. There is a link to this on http://www.ora.com/davenport NOTE: This does not work yet.

#### Installation

There is no standard place where the DocBook Modular Stylesheets are installed.

GTK-Doc's configure script searches these 3 directories automatically:

`/usr/lib/sgml/stylesheets/nwalsh-modular` (used by RedHat)

`/usr/lib/dsssl/stylesheets/docbook` (used by Debian)

`/usr/share/sgml/docbkdsl` (used by SuSE)

If you have the stylesheets installed somewhere else, you need to configure GTK-Doc using the option: `--with-dsssl-dir=<PATH_TO_TOPLEVEL_STYLESHEETS_DIR>`

### About GTK-Doc

(FIXME)

(History, authors, web pages, license, future plans, comparison with other similar systems.)

### About this Manual

(FIXME)

(who it is meant for, where you can get it, license)

## Setting up your project

The next sections describe what steps to perform to integrate GTK-Doc into your project. Theses sections assume we work on a project called 'meep'. This project contains a library called 'libmeep' and an end-user app called 'meeper'. We also assume you will be using autoconf and automake. In addition section plain makefiles or other build systems will describe the basics needed to work in a different build setup.

### Setting up a skeleton documentation

Under your top-level project directory create folders called docs/reference (this way you can also have docs/help for end-user documentation). It is recommended to create another subdirectory with the name of the doc-package. For packages with just one library this step is not necessary.

This can then look as shown below:

Example directory structure

    meep/
      docs/
        reference/
          libmeep/
          meeper/
      src/
        libmeep/
        meeper/

### Integration with autoconf

Very easy! Just add one line to your `configure.ac` script.

Integration with autoconf

    # check for gtk-doc
    GTK_DOC_CHECK([1.14],[--flavour no-tmpl])

This will require all developers to have gtk-doc installed. If it is okay for your project to have optional api-doc build setup, you can solve this as below. Keep it as is, as gtkdocize is looking for `GTK_DOC_CHECK` at the start of a line.

Keep gtk-doc optional

    # check for gtk-doc
    m4_ifdef([GTK_DOC_CHECK], [
    GTK_DOC_CHECK([1.14],[--flavour no-tmpl])
    ],[
    AM_CONDITIONAL([ENABLE_GTK_DOC], false)
    ])

The first argument is used to check for the gtkdocversion at configure time. The 2nd, optional argument is used by gtkdocize. The GTK_DOC_CHECK macro also adds several configure switches:

1. --with-html-dir=PATH : path to installed docs

2. --enable-gtk-doc : use gtk-doc to build documentation [default=no]

3. --enable-gtk-doc-html : build documentation in html format [default=yes]

4. --enable-gtk-doc-pdf : build documentation in pdf format [default=no]

GTK-Doc is disabled by default! Remember to pass the option `'--enable-gtk-doc'` to the next `configure` run. Otherwise pregenerated documentation is installed (which makes sense for users but not for developers).

Furthermore it is recommended that you have the following line inside you `configure.ac` script. This allows gtkdocize to automatically copy the macro definition for `GTK_DOC_CHECK` to your project.

Preparation for gtkdocize

    AC_CONFIG_MACRO_DIR(m4)

### Integration with automake

First copy the `Makefile.am` from the examples subdirectory of the gtkdoc-sources to your project's API documentation directory ( `./docs/reference/<package>`). If you have multiple doc-packages repeat this for each one.

The next step is to edit the settings inside the `Makefile.am`. All the settings have a comment above that describes their purpose. Most settings are extra flags passed to the respective tools. Every tool has a variable of the form `<TOOLNAME>_OPTIONS`. All the tools support `--help` to list the supported parameters.

You may also want to enable GTK-Doc for the distcheck make target. Just add the one line shown in the next example to your top-level `Makefile.am`:

Enable GTK-Doc during make distcheck

    DISTCHECK_CONFIGURE_FLAGS=--enable-gtk-doc

### Integration with autogen

Most projects will have an `autogen.sh` script to setup the build infrastructure after a checkout from version control system (such as cvs/svn/git). GTK-Doc comes with a tool called gtkdocize which can be used in such a script. It should be run before autoheader, automake or autoconf.

Running gtkdocize from autogen.sh

    gtkdocize || exit 1

When running gtkdocize it copies `gtk-doc.make` to your project root (or any directory specified by the `--docdir` option). It also checks you configure script for the `GTK_DOC_CHECK` invocation. This macro can be used to pass extra parameters to gtkdocize.

Historically GTK-Doc was generating template files where developers entered the docs. This turned out to be not so good (e.g. the need for having generated files under version control). Since GTK-Doc 1.9 the tools can get all the information from source comments and thus the templates can be avoided. We encourage people to keep documentation in the code. gtkdocize supports now a `--flavour no-tmpl` option that chooses a makefile that skips tmpl usage totally. Besides adding the option directly to the command invocation, they can be added also to an environment variable called GTKDOCIZE_FLAGS or set as a 2nd parameter in GTK_DOC_CHECK macro in the configure script. If you have never changed file in tmpl by hand and migrating from older gtkdoc versions, please remove the directory (e.g. from version control system).

### Running the doc build

After the previous steps it's time to run the build. First we need to rerun `autogen.sh`. If this script runs configure for you, then give it the `--enable-gtk-doc` option. Otherwise manually run `configure` with this option afterwards.

The first make run generates several additional files in the doc-directories. The important ones are: `<package>.types`, `<package>-docs.xml` (in the past .sgml), `<package>-sections.txt`.

Running the doc build

    ./autogen.sh --enable-gtk-doc
    make

Now you can point your browser to `docs/reference/<package>/index.html`. Yes, it's a bit disappointing still. But hang-on, during the next chapter we tell you how to fill the pages with life.

### Integration with version control systems

As a rule of the thumb, it's those files you edit, that should go under version control. For typical projects it's these files: `<package>.types`, `<package>-docs.xml` (in the past .sgml), `<package>-sections.txt`, `Makefile.am`

### Integration with plain makefiles or other build systems

In the case one does not want to use automake and therefore `gtk-doc.mak` one will need to call the gtkdoc tools in the right order in own makefiles (or other build tools).

Documentation build steps

    DOC_MODULE=meep
    // sources have changed
    gtkdoc-scan --module=$(DOC_MODULE) --source-dir=...
    gtkdoc-scangobj --module=$(DOC_MODULE)
    gtkdoc-mkdb --module=$(DOC_MODULE) --output-format=xml
    // xml files have changed
    mkdir html
    cd html && gtkdoc-mkhtml $(DOC_MODULE) ../meep-docs.xml
    gtkdoc-fixxref --module=$(DOC_MODULE) --module-dir=html

One will need to look at the `Makefile.am` and `gtk-doc.mak` to pick the extra options needed.

## Documenting the code

GTK-Doc uses source code comment with a special syntax for code documentation. Further it retrieves information about your project structure from other sources. During the next section you will find all information about the syntax of the comments.

Documentation placement

In the past most documentation had to be filled into files residing inside the `tmpl` directory. This has the disadvantages that the information is often not updated and also that the file tend to cause conflicts with version control systems.

The avoid the aforementioned problems we suggest putting the documentation inside the sources. This manual will only describe this way of documenting code.

The scanner can handle the majority of C headers fine. In the case of receiving warnings from the scanner that look like a special case, one can hint GTK-Doc to skip over them.

GTK-Doc comment block

    #ifndef __GTK_DOC_IGNORE__
    /* unparseable code here */
    #endif

### Documentation comments

A multiline comment that starts with an additional '*' marks a documentation block that will be processed by the GTK-Doc tools.

GTK-Doc comment block

    /**
     * identifier:
     * documentation ...
     */

The 'identifier' is one line with the name of the item the comment is related to. The syntax differs a little depending on the item. (TODO add table showing identifiers)

The 'documentation' block is also different for each symbol type. Symbol types that get parameters such as functions or macros have the parameter description first followed by a blank line (just a '*'). Afterwards follows the detailed description. All lines (outside program listings and CDATA sections) just containing a ' *' (blank-asterisk) are converted to paragraph breaks. If you don't want a paragraph break, change that into ' * ' (blank-asterisk-blank-blank). This is useful in preformatted text (code listings).

When documenting code, describe two aspects:

- What it is: The name for a class or function can sometimes be misleading for people coming from a different background.

- What it does: Tell about common uses. Put it in relation with the other API.

One advantage of hyper-text over plain-text is the ability to have links in the document. Writing the correct markup for a link can be tedious though. GTK-Doc comes to help by providing several useful abbreviations.

- Use function() to refer to functions or macros which take arguments.

- Use @param to refer to parameters. Also use this when referring to parameters of other functions, related to the one being described.

- Use %constant to refer to a constant, e.g. %G_TRAVERSE_LEAFS.

- Use #symbol to refer to other types of symbol, e.g. structs and enums and macros which don't take arguments.

- Use #Object::signal to refer to a GObject signal.

- Use #Object:property to refer to a GObject property.

- Use #Struct.field to refer to a field inside a structure.

If you need to use the special characters '<', '>', '()', '@', '%', or '#' in your documentation without GTK-Doc changing them you can use the XML entities "&lt;", "&gt;", "&lpar;", "&rpar;", "&commat;", "&percnt;" and "&num;" respectively or escape them with a backslash '\'.

DocBook can do more than just links. One can also have lists, tables and examples. To enable the usage of docbook SGML/XML tags inside doc-comments you need to have `--xml-mode` or `--sgml-mode` in the variable MKDB_OPTIONS inside `Makefile.am`.

Since GTK-Doc-1.18 the tool supports a subset or the markdown language. One can use it for sub-headings and simple itemized lists. On older GTK-Doc versions the content will be rendered as it (the list items will appear in one line separated by dashes).

GTK-Doc comment block using markdown

    /**
     * identifier:
     *
     * documentation ...
     *
     * # Sub heading #
     *
     * more documentation:
     * - list item 1
     * - list item 2
     *
     * Even more docs.
     */

As already mentioned earlier GTK-Doc is for documenting public API. Thus one cannot write documentation for static symbols. Nevertheless it is good to comment those symbols too. This helps other to understand you code. Therefore we recommend to comment these using normal comments (without the 2nd '*' in the first line). If later the function needs to be made public, all one needs to do is to add another '*' in the comment block and insert the symbol name at the right place inside the sections file.

### Documenting sections

Each section of the documentation contains information about one class or module. To introduce the component one can write a section block. The short description is also used inside the table of contents. All the @fields are optional.

Section comment block

    /**
     * SECTION:meepapp
     * @short_description: the application class
     * @title: Meep application
     * @section_id:
     * @see_also: #MeepSettings
     * @stability: Stable
     * @include: meep/app.h
     * @image: application.png
     *
     * The application class handles ...
     */

SECTION:<name>

  The name links the section documentation to the respective part in the `<package>-sections.txt` file. The name give here should match the <FILE> tag in the `<package>-sections.txt` file.

@short_description

  A one line description of the section, that later will appear after the links in the TOC and at the top of the section page.

@title

  The section title defaults to <name> from the SECTION declaration. It can be overridden with the @title field.

@section_id

  Overrides the use of title as a section identifier. For GObjects the <title> is used as a section_id and for other sections it is <MODULE>-<title>.

@see_also

  A list of symbols that are related to this section.

@stability

  An informal description of the stability level this API has. We recommend the use of one of these terms:

  - Stable - The intention of a Stable interface is to enable arbitrary third parties to develop applications to these interfaces, release them, and have confidence that they will run on all minor releases of the product (after the one in which the interface was introduced, and within the same major release). Even at a major release, incompatible changes are expected to be rare, and to have strong justifications.

  - Unstable - Unstable interfaces are experimental or transitional. They are typically used to give outside developers early access to new or rapidly changing technology, or to provide an interim solution to a problem where a more general solution is anticipated. No claims are made about either source or binary compatibility from one minor release to the next.

  - Private - An interface that can be used within the GNOME stack itself, but that is not documented for end-users. Such functions should only be used in specified and documented ways.

  - Internal - An interface that is internal to a module and does not require end-user documentation. Functions that are undocumented are assumed to be Internal.

@include

  The `#include` files to show in the section synopsis (a comma separated list), overriding the global value from the section file or command line. This item is optional.

@image

  The image to display at the top of the reference page for this section. This will often be some sort of a diagram to illustrate the visual appearance of a class or a diagram of its relationship to other classes. This item is optional.

To avoid unnecessary recompilation after doc-changes put the section docs into the c-source where possible.

### Documenting symbols

Each symbol (function, macro, struct, enum, signal and property) is documented in a separate block. The block is best placed close to the definition of the symbols so that it is easy to keep them in sync. Thus functions are usually documented in the c-source and macros, structs and enums in the header file.

#### General tags

You can add versioning information to all documentation elements to tell when an API was introduced, or when it was deprecated.

Versioning Tags

Since:

  Description since which version of the code the API is available.

Deprecated:

  Paragraph denoting that this function should no be used anymore. The description should point the reader to the new API.

(FIXME : Stability information)

General tags

    /**
     * foo_get_bar:
     * @foo: some foo
     *
     * Retrieves @foo's bar.
     *
     * Returns: @foo's bar
     *
     * Since: 2.6
     * Deprecated: 2.12: Use foo_baz_get_bar() instead.
     */
    Bar *
    foo_get_bar(Foo *foo)
    {
    ...

#### Function comment block

Please remember to:

- Document whether returned objects, lists, strings, etc, should be freed/unrefed/released.

- Document whether parameters can be NULL, and what happens if they are.

- Mention interesting pre-conditions and post-conditions where appropriate.

Gtk-doc assumes all symbols (macros, functions) starting with '_' are private. They are treated like static functions.

Also, take a look at GObject Introspection annotation tags: http://live.gnome.org/GObjectIntrospection/Annotations

Function comment block

    /**
     * function_name:
     * @par1:  description of parameter 1. These can extend over more than
     * one line.
     * @par2:  description of parameter 2
     * @...: a %NULL-terminated list of bars
     *
     * The function description goes here. You can use @par1 to refer to parameters
     * so that they are highlighted in the output. You can also use %constant
     * for constants, function_name2() for functions and #GtkWidget for links to
     * other declarations (which may be documented elsewhere).
     *
     * Returns: an integer.
     *
     * Since: 2.2
     * Deprecated: 2.18: Use other_function() instead.
     */

Function tags

Returns:

  Paragraph describing the returned result.

@...:

  In case the function has variadic arguments, you should use this tag (@Varargs: does also work for historic reasons).

#### Property comment block

Property comment block

    /**
     * SomeWidget:some-property:
     *
     * Here you can document a property.
     */
    g_object_class_install_property (object_class, PROP_SOME_PROPERTY, ...);

#### Signal comment block

Please remember to:

- Document when the signal is emitted and whether it is emitted before or after other signals.

- Document what an application might do in the signal handler.

Signal comment block

    /**
     * FooWidget::foobarized:
     * @widget: the widget that received the signal
     * @foo: some foo
     * @bar: some bar
     *
     * The ::foobarized signal is emitted each time someone tries to foobarize @widget.
     */
    foo_signals[FOOBARIZE] =
      g_signal_new ("foobarize",
                    ...

#### Struct comment block

Struct comment block

    /**
     * FooWidget:
     * @bar: some #gboolean
     *
     * This is the best widget, ever.
     */
    typedef struct _FooWidget {
      /*< private >*/
      GtkWidget parent;

      /*< public >*/
      gboolean bar;
    } FooWidget;

Use `/*< private >*/` before the private struct fields you want to hide. Use `/*< public >*/` for the reverse behaviour.

Struct comment blocks can also be used for GObjects and GObjectClasses. It is usually a good idea to add a comment block for a class, if it has vmethods (as this is how they can be documented). For the GObject itself one can use the related section docs, having a separate block for the instance struct would be useful if the instance has public fields. One disadvantage here is that this creates two index entries of the same name (the structure and the section).

#### Enum comment block

Enum comment block

    /**
     * Something:
     * @SOMETHING_FOO: something foo
     * @SOMETHING_BAR: something bar
     *
     * Enum values used for the thing, to specify the thing.
     */
    typedef enum {
      SOMETHING_FOO,
      SOMETHING_BAR,
      /*< private >*/
      SOMETHING_COUNT
    } Something;

Use `/*< private >*/` before the private enum values you want to hide. Use `/*< public >*/` for the reverse behaviour.

### Useful DocBook tags

Here are some DocBook tags which are most useful when documenting the code.

To link to another section in the GTK docs:

    <link linkend="glib-Hash-Tables">Hash Tables</link>

The linkend is the SGML/XML id on the top item of the page you want to link to. For most pages this is currently the part ("gtk", "gdk", "glib") and then the page title ("Hash Tables"). For widgets it is just the class name. Spaces and underscores are converted to '-' to conform to SGML/XML.

To refer to an external function, e.g. a standard C function:

    <function>...</function>

To include example code:

    <example>
      <title>Using a GHashTable.</title>
      <programlisting>
          ...
      </programlisting>
    </example>

or possibly this, for very short code fragments which don't need a title:

    <informalexample>
      <programlisting>
      ...
      </programlisting>
    </informalexample>

For the latter GTK-Doc also supports an abbreviation: |[ ... ]|

To include bulleted lists:

    <itemizedlist>
      <listitem>
        <para>
          ...
        </para>
      </listitem>
      <listitem>
        <para>
          ...
        </para>
      </listitem>
    </itemizedlist>

To include a note which stands out from the text:

    <note>
      <para>
        Make sure you free the data after use.
      </para>
    </note>

To refer to a type:

    <type>unsigned char</type>

To refer to an external structure (not one described in the GTK docs):

    <structname>XFontStruct</structname>

To refer to a field of a structure:

    <structfield>len</structfield>

To refer to a class name, we could possibly use:

    <classname>GtkWidget</classname>

but you'll probably be using #GtkWidget instead (to automatically create a link to the GtkWidget page - see the abbreviations).

To emphasize text:

    <emphasis>This is important</emphasis>

For filenames use:

    <filename>/home/user/documents</filename>

To refer to keys use:

    <keycombo><keycap>Control</keycap><keycap>L</keycap></keycombo>

## Filling the extra files

There are a couple of extra files, that need to be maintained along with the inline source code comments: `<package>.types`, `<package>-docs.xml` (in the past .sgml), `<package>-sections.txt`.

### Editing the types file

If your library or application includes GObjects, you want their signals, arguments/parameters and position in the hierarchy to be shown in the documentation. All you need to do, is to list the `xxx_get_type` functions together with their include inside the `<package>.types` file.

Example types file snippet

    #include <gtk/gtk.h>

    gtk_accel_label_get_type
    gtk_adjustment_get_type
    gtk_alignment_get_type
    gtk_arrow_get_type

Since GTK-Doc 1.8 gtkdoc-scan can generate this list for you. Just add "--rebuild-types" to SCAN_OPTIONS in `Makefile.am`. If you use this approach you should not dist the types file nor have it under version control.

### Editing the master document

GTK-Doc produces documentation in DocBook SGML/XML. When processing the inline source comments, the GTK-Doc tools generate one documentation page per class or module as a separate file. The master document includes them and place them in an order.

While GTK-Doc creates a template master document for you, later run will not touch it again. This means that one can freely structure the documentation. That includes grouping pages and adding extra pages. GTK-Doc has now a test suite, where also the master-document is recreated from scratch. Its a good idea to look at this from time to time to see if there are some new goodies introduced there.

Do not create tutorials as extra documents. Just write extra chapters. The benefit of directly embedding the tutorial for your library into the API documentation is that it is easy to link for the tutorial to symbol documentation. Apart chances are higher that the tutorial gets updates along with the library.

So what are the things to change inside the master document? For a start is only a little. There are some placeholders (text in square brackets) there which you should take care of.

Master document header

    <bookinfo>
      <title>MODULENAME Reference Manual</title>
      <releaseinfo>
        for MODULENAME [VERSION]
        The latest version of this documentation can be found on-line at
        <ulink role="online-location" url="http://[SERVER]/MODULENAME/index.html">http://[SERVER]/MODULENAME/</ulink>.
      </releaseinfo>
    </bookinfo>

    <chapter>
      <title>[Insert title here]</title>

### Editing the section file

The section file is used to organise the documentation output by GTK-Doc. Here one specifies which symbol belongs to which module or class and control the visibility (public or private).

The section file is a plain text file with XML-like syntax (using tags). Blank lines are ignored and lines starting with a '#' are treated as comment lines.

The <FILE> ... </FILE> tag is used to specify the file name, without any suffix. For example, using '<FILE>gnome-config</FILE>' will result in the section declarations being output in the template file `tmpl/gnome-config.sgml`, which will be converted into the DocBook SGML/XML file `sgml/gnome-config.sgml` or the DocBook XML file `xml/gnome-config.xml`. (The name of the HTML file is based on the module name and the section title, or for GObjects it is based on the GObjects class name converted to lower case).

The <TITLE> ... </TITLE> tag is used to specify the title of the section. It is only useful before the templates (if used) are initially created, since the title set in the template file overrides this. Also if one uses SECTION comment in the sources, this is obsolete.

You can group items in the section by using the <SUBSECTION> tag. Currently it outputs a blank line between subsections in the synopsis section. You can also use <SUBSECTION Standard> for standard GObject declarations (e.g. the functions like g_object_get_type and macros like G_OBJECT(), G_IS_OBJECT() etc.). Currently these are left out of the documentation. You can also use <SUBSECTION Private> for private declarations which will not be output (it is a handy way to avoid warning messages about unused declarations). If your library contains private types which you don't want to appear in the object hierarchy and the list of implemented or required interfaces, add them to a Private subsection. Whether you would place GObject and GObjectClass like structs in public or Standard section depends if they have public entries (variables, vmethods).

You can also use <INCLUDE> ... </INCLUDE> to specify the #include files which are shown in the synopsis sections. It contains a comma-separate list of #include files, without the angle brackets. If you set it outside of any sections, it acts for all sections until the end of the file. If you set it within a section, it only applies to that section.

## Controlling the result

A GTK-Doc run generates report files inside the documentation directory. The generated files are named: `<package>-undocumented.txt`, `<package>-undeclared.txt` and `<package>-unused.txt`. All those are plain text files that can be viewed and postprocessed easily.

The `<package>-undocumented.txt` file starts with the documentation coverage summary. Below are two sections divided by blank lines. The first section lists undocumented or incomplete symbols. The second section does the same for section docs. Incomplete entries are those, which have documentation, but where e.g. a new parameter has been added.

The `<package>-undeclared.txt` file lists symbols given in the `<package>-sections.txt` but not found in the sources. Check if they have been removed or if they are misspelled.

The `<package>-unused.txt` file lists symbol names, where the GTK-Doc scanner has found documentation, but does not know where to put it. This means that the symbol has not yet been added to the `<package>-sections.txt` file.

Enable or add the `TESTS=$(GTKDOC_CHECK)` line in Makefile.am. If at least GTK-Doc 1.9 is installed, this will run sanity checks during `make check` run.

One can also look at the files produced by the source code scanner: `<package>-decl-list.txt` and `<package>-decl.txt`. The first one can be compared with the section file if that is manually maintained. The second lists all declarations from the headers. If a symbol is missing one could check if this file contains it.

If the project is GObject based, one can also look into the files produced by the object scanner: `<package>.args.txt`, `<package>.hierarchy.txt`, `<package>.interfaces.txt`, `<package>.prerequisites.txt` and `<package>.signals.txt`. If there are missing symbols in any of those, one can ask gtkdoc to keep the intermediate scanner file for further analysis, by running it as `GTK_DOC_KEEP_INTERMEDIATE=1 make`.

## Documenting other interfaces

So far we have been using GTK-Doc to document the API of code. The next sections contain suggestions how the tools can be used to document other interfaces too.

### Command line options and man pages

As one can generate man pages for a docbook refentry as well, it sounds like a good idea to use it for that purpose. This way the interface is part of the reference and one gets the man-page for free.

#### Document the tool

Create one refentry file per tool. Following our example we would call it `meep/docs/reference/meeper/meep.xml`. For the xml tags that should be used and can look at generated file in the xml subdirectory as well as examples e.g. in glib.

#### Adding the extra configure check

Extra configure checks

    AC_ARG_ENABLE(man,
                  [AC_HELP_STRING([--enable-man],
                                  [regenerate man pages from Docbook [default=no]])],enable_man=yes,
                  enable_man=no)

    AC_PATH_PROG([XSLTPROC], [xsltproc])
    AM_CONDITIONAL(ENABLE_MAN, test x$enable_man != xno)

#### Adding the extra makefile rules

Extra configure checks

    man_MANS = \
           meeper.1

    if ENABLE_GTK_DOC
    if ENABLE_MAN

    %.1 : %.xml
            @XSLTPROC@ -nonet http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl $<

    endif
    endif

    BUILT_EXTRA_DIST = $(man_MANS)
    EXTRA_DIST += meep.xml

### DBus interfaces

(FIXME: http://hal.freedesktop.org/docs/DeviceKit/DeviceKit.html, http://cgit.freedesktop.org/DeviceKit/DeviceKit/tree/doc/dbus)

## Frequently asked questions

Question Answer
- No class hierarchy. The objects `xxx_get_type()` function has not been entered into the `<package>.types` file.
- Still no class hierarchy. Missing or wrong naming in `<package>-sections.txt` file (see explanation).
- Damn, I have still no class hierarchy. Is the object name (name of the instance struct, e.g. GtkWidget) part of the normal section (don't put this into Standard or Private subsections).
- No symbol index. Does the `<package>-docs.{xml,sgml}` contain a index that xi:includes the generated index?
- Symbols are not linked to their doc-section. Is the doc-comment using the correct markup (added #,% or ())? Check if the gtkdoc-fixxref warns about unresolvable xrefs.
- A new class does not appear in the docs. Is the new page xi:included from `<package>-docs.{xml,sgml}`.
- A new symbol does not appear in the docs. Is the doc-comment properly formatted. Check for spelling mistakes in the begin of the comment. Check if the gtkdoc-fixxref warns about unresolvable xrefs. Check if the symbol is correctly listed in the `<package>-sections.txt` in a public subsection.
- A type is missing from the class hierarchy. If the type is listed in `<package>.hierarchy` but not in `xml/tree_index.sgml` then double check that the type is correctly placed in the `<package>-sections.txt`. If the type instance (e.g. GtkWidget) is not listed or incidentialy makred private it will not be shown.
- I get foldoc links for all gobject annotations. Check that `xml/annotation-glossary.xml` is xi:included from `<package>-docs.{xml,sgml}`.
- Parameter described in source code comment block but does not exist Check if the prototype in the header has different parameter names as in the source.
- multiple "IDs" for constraint linkend: XYZ Symbol XYZ appears twice in `<package>-sections.txt` file.
- Element typename in namespace '' encountered in para, but no template matches.

## Tools related to gtk-doc

GtkDocPlugin - a Trac GTK-Doc integration plugin, that adds API docs to a trac site and integrates with the trac search.

Gtkdoc-depscan - a tool (part of gtk-doc) to check used API against since tags in the API to determine the minimum required version.

&FDL;