path: root/src/kconfig_compiler/README.dox

/**
\page kconfig_compiler The KDE Configuration Compiler

kconfig_compiler generates C++ source code from an XML file containing
information about configuration options (.kcfg) and a file that provides
the code generation options (.kcfgc) The generated class is based on
KConfigSkeleton and provides an API for the application to access its
configuration data.

The generated C++ source code is output to a .h and a .cpp file, whose base
name is the same as that of the .kcfgc file.

\section kcfg_format The .kcfg XML file format: description of the configuration skeleton

The structure of the .kcfg file is described by its DTD kcfg.xsd.

The \<kcfgfile\> tag may contain either the "name" attribute, which should be the name
of the configuration file described, or the "arg" attribute, which, if set to
"true", will allow you to pass the KSharedConfig::Ptr object to use.

If neither "name" nor "arg" is set, the default configuration file
("\<appname\>rc") will be used.

The \<include\> tags are optional and may contain C++ header files that
are needed to compile the code needed to compute default values. To generate
a \#include "..." statement instead of \#include \<...\>, enclose the header
file name in double quotes (e.g. \<include\>"header.h"\</include\>).

The remaining entries in the XML file are grouped by the tag \<group\>
which describes the corresponding group in the configuration file.

The individual entries must have at least a name or a key. The key is used
as the key in the config file, while the name is used to create accessor and
modifier functions. If \<key\> is given, but not \<name\>, the name is
constructed by removing all spaces from \<key\>. If \<name\> is given, but
not \<key\>, the key is the same as \<name\>.

An entry must also have a type. The list of allowable types is
specified in the DTD and loosely follows the list of types supported
by the QVariant with exception of the clearly binary types
(e.g. Pixmap, Image...) which are not supported. Besides those basic
types the following special types are supported:

<dl>
  <dt>Path</dt>
  <dd>
    This is a string that is specially treated as a file-path.
    In particular paths in the home directory are prefixed with $HOME in
    when being stored in the configuration file.
  </dd>

  <dt>Enum</dt>
  <dd>
    This indicates an enumeration. The possible enum values and optional
    enum name should be provided via the \<choices\> tag. Enum values are
    accessed as integers by the application but stored as strings in the
    configuration file. This makes it possible to add more values at a later
    date without breaking compatibility.
  </dd>

  <dt>IntList</dt>
  <dd>
    This indicates a list of integers. This information is provided
    to the application as QList<int>. Useful for storing QSplitter
    geometries.
  </dd>

  <dt>Color</dt>
  <dd>
    Isn't a special type but has special input. It is generated as QColor.
    Any valid input to QColor(QString) can be used (hex or SVG keyword notation)
    as well as a special format r,g,b,a where the a denotes the alpha channel and
    may be omitted.
  </dd>
</dl>

An entry can optionally have a default value which is used as default when
the value isn't specified in any config file. Default values are interpreted
as literal constant values. If a default value needs to be computed
or if it needs to be obtained from a function call, the \<default\> tag
should contain the code="true" attribute. The contents of the \<default\>
tag is then considered to be a C++ expression. Note that in this case you
might have to add an \<include\> tag as described above, or a
SourceIncludeFiles entry in the .kcfgc file as described below, so that the
code which computes the default value can be compiled.

Additional code for computing default values can be provided outside any
entry definition via the \<code\> tag. The contents of the \<code\> tag is
inserted as-is. A typical use for this is to compute a common default value
which can then be referenced by multiple entries that follow.

\section kcfgc_format The .kcfgc file format: code generation options

The options for generating the C++ sources are read from the file with the
extension .kcfgc. To generate a class add the corresponding kcfgc file to the
SOURCES line in the Makefile.am.

The following options are read from the kcfgc file:


<dl>
  <dt>File=\<string\></dt>
  <dd>
    Default: \<programname\>.kcfg \n
    Name of kcfg file containing the options the class is generated for
    <!-- what? -->
  </dd>

  <dt>HeaderExtension=\<string\></dt>
  <dd>
    Default: h \n
    Since KF 5.57 \n
    Extension to use for the name of the generated C++ header files.
  </dd>

  <dt>SourceExtension=\<string\></dt>
  <dd>
    Default: cpp \n
    Since KF 5.57 \n
    Extension to use for the name of the generated C++ source file.
  </dd>

  <dt>NameSpace=\<string\></dt>
  <dd>
    Optional namespace for generated class
  </dd>

  <dt>ClassName=\<string\></dt>
  <dd>
    Name of generated class (required)
  </dd>

  <dt>Inherits=\<string\></dt>
  <dd>
    Default: KConfigSkeleton \n
    Class the generated class inherits from.

    This class must inherit KConfigSkeleton and must provide a default
    constructor (kcfgfile not specified), a constructor taking a
    QString argument (kcfgfile with "name" attribute) and a constructor
    taking a KSharedConfig::Ptr as argument (kcfgfile with "arg" attribute).
    Please refer to the documentation of KConfigSkeleton.
  </dd>

  <dt>Visibility=\<string\></dt>
  <dd>
    Inserts visibility directive (for example KDE_EXPORT) between
    "class" keyword and class name in header file
  </dd>

  <dt>Singleton=\<bool\></dt>
  <dd>
    Default: false \n
    Generated class is a singleton.
  </dd>

  <dt>CustomAdditions=\<bool\></dt>
  <dd>
    <!-- what? -->
  </dd>

  <dt>MemberVariables=\<string\></dt>
  <dd>
    Values: public, protected, private, dpointer \n
    Default: private \n
    C++ access modifier used for member variables holding the configuration
    values
  </dd>

  <dt>IncludeFiles=\<string\>, \<string\> ...</dt>
  <dd>
    Names of files to be included in the header of the generated class.

    Enclose a file name in (escaped) double quotes to generate
    \#include "..." instead of \#include \<...\>.
  </dd>

  <dt>SourceIncludeFiles=\<string\>, \<string\> ...</dt>
  <dd>
    Names of files to be included in the source file of the generated class.

    Enclose a file name in (escaped) double quotes to generate
    \#include "..." instead of \#include \<...\>.
  </dd>

  <dt>Mutators=\<value\></dt>
  <dd>
    Values: true, false or a comma separated list of options \n
    Default: false \n
    If true, mutator functions for all configuration options are generated.
    If false, no mutator functions are generated. If a list is provided,
    mutator functions are generated for the options that are listed.
  </dd>

  <dt>Notifiers=\<value\></dt>
  <dd>
    Values: true, false or a comma separated list of options \n
    Default: false \n
    If true, entries will be written with the <b>Notify</b> flag enabled,
    so changes can be detected using <b>KConfigWatcher</b>.
    If a list is provided, the options that are listed are written with
    said flag.
  </dd>

  <dt>DefaultValueGetters=\<value\></dt>
  <dd>
    Values: true, false or a comma separated list of options \n
    Default: false \n
    If true, functions to return the default value of all configuration options
    are generated. If false, no default value functions are generated. If a list
    is provided, default value functions are generated for the options that are listed.
  </dd>

  <dt>ItemAccessors=\<bool\></dt>
  <dd>
    Default: false \n
    Generate accessor functions for the KConfigSkeletonItem objects
    corresponding to the configuration options. If <b>SetUserTexts</b> is set,
    <b>ItemAccessors</b> also has to be set.
  </dd>

  <dt>SetUserTexts=\<bool\></dt>
  <dd>
    Default: false \n
    Set the label and whatthis texts of the items from the kcfg file.
    If <b>SetUserTexts</b> is set, <b>ItemAccessors</b> also has to be set.
  </dd>

  <dt>GlobalEnums=\<bool\></dt>
  <dd>
    Default: false \n
    If set to true all choices of Enum items will be created in the global
    scope of the generated class. If set to false, each Enum item whose enum is not
    explicitly named will get its own namespace for its choices.
  </dd>

  <dt>UseEnumTypes=\<bool\></dt>
  <dd>
    Default: false \n
    If set to true, all Enum items whose enums are named will use enum types for
    the return value of accessor functions and for the parameter of mutator
    functions. This eliminates the need to cast accessor return values to the enum
    type if you want to use the enum type in your own code. If set to false,
    accessor return values and mutator parameters will be of type int.
  </dd>

  <dt>ForceStringFilename=\<bool\></dt>
  <dd>
    Default: false \n
    If set to true, forces the first parameter of the generated class
    to be a QString when using an argument for the filename.
    This is useful to specify at runtime the filename of the configuration class.
  </dd>

  <dt>GenerateProperties=\<bool\></dt>
  <dd>
    Default: false \n
    If set to true, a Q_PROPERTY will be generated for each member variable holding a
    configuration value and the Q_OBJECT macro will be added to the generated class.
    Note that you will also need to pass the GENERATE_MOC option to the
    kconfig_add_kcfg_files macro.
  </dd>


  <dt>ParentInConstructor=\<bool\></dt>
  <dd>
    Default: false \n
    If set to true, the generated constructor will take an additional QObject*
    parameter that will be used as the object's parent.
    This is useful when working with KQuickAddons::ManagedConfigModule
    to set it as the parent of the generated class to allow automatic
    settings discovery and handle the deallocation.
    Note this parameter is incompatible with <b>Singleton</b> set to true.
  </dd>

  <dt>TranslationSystem=\<string\></dt>
  <dd>
    Default: qt \n
    Set the translation system for label, tooltip and whatsthis text in generated KConfigSkeleton.
    Set the value to <b>kde</b> to use the KDE Framework translation system, see KI18n.
  </dd>

  <dt>TranslationDomain=\<value\></dt>
  <dd>
    When <b>TranslationSystem=kde</b> is set, allow to specify the domain in which to look for translations.
  </dd>

</dl>


\section entry_options Advanced entry options

There are several possibilities to parameterize entries.

\subsection parametrized_entries Parameterized entries

An entry can be parameterized using a fixed range parameter specified with
the \<parameter\> tag. Such parameter can either be an Enum or an int. An Enum
parameter should specify the possible enumeration values with the \<choices\>
tag. An int parameter should specify its maximum value. Its minimum value
is always 0.

A parameterized entry is expanded to a number of entries, one for each
value in the parameter range. The name and key should contain a reference
to the parameter in the form of $(parameter-name). When expanding the entries
the $(parameter-name) part is replaced with the value of the parameter.
In the case of an Enum parameter it is replaced with the name of the
enumuration value. In the case of an int parameter it is replaced with
the numeric value of the parameter.

Parameterized entries all share the same default value unless different
default values have been specified for specific parameter values.
This can be done with the param= attribute of the \<default\>. When a
param attribute is specified the default value only applies to that
particular parameter value.

Example 1:
\code{.xml}
<entry name="Color$(ColorIndex)" type="Color" key="color_$(ColorIndex)">
  <parameter name="ColorIndex" type="Int" max="3"/>
  <default param="0">#ff0000</default>
  <default param="1">#00ff00</default>
  <default param="2">#0000ff</default>
  <default param="3">#ffff00</default>
</entry>
\endcode

The above describes 4 color configuration entries with the following defaults:

\verbatim
color_0=#ff0000
color_1=#00ff00
color_2=#0000ff
color_3=#ffff00
\endverbatim

The configuration options will be accessible to the application via
a QColor color(int ColorIndex) and a
void setColor(int ColorIndex, const QColor &v) function.

Example 2:
\code{.xml}
<entry name="Sound$(SoundEvent)" type="String" key="sound_$(SoundEvent)">
  <parameter name="SoundEvent" type="Enum">
    <values>
      <value>Explosion</value>
      <value>Crash</value>
      <value>Missile</value>
    </values>
  </parameter>
  <default param="Explosion">boom.wav</default>
  <default param="Crash">crash.wav</default>
  <default param="Missile">missile.wav</default>
</entry>
\endcode

The above describes 3 string configuration entries with the following defaults:

\verbatim
sound_Explosion=boom.wav
sound_Crash=crash.wav
sound_Missile=missile.wav
\endverbatim

The configuration options will be accessible to the application via
a QString sound(int SoundEvent) and a
void setSound(int SoundEvent, const QString &v) function.

\subsection parametrized_groups Parameterized groups

A group name can be parametrized using a parameter given to the KConfigSkeleton
instance (which means this feature cannot be used with singleton classes).

Example 1:
\code{.xml}
<kcfgfile name="testrc">
  <parameter name="groupname"/>
</kcfgfile>
<group name="$(groupname)">
  <entry key="Text" type="string">
  </entry>
</group>
\endcode

In this case passing "Group2" as the 'groupname' parameter to the generated class
will make it use group "Group2" for the entry "Text".

By setting the stateConfig attribute of kcfgfile to "true", KSharedConfig::openStateConfig is used.
This should be used when one stores volatile data, like window sizes or autocompletion texts.
It is recommended to have at least two separate kcfg files for the different kinds of data.
NOTE: This option is ignored when ForceStringFilename is set.

\subsection enums Enums

By default, if <b>GlobalEnums</b> is set to false, a separate named enum will be generated
for each Enum entry. Since each enum is defined in a little enclosing class of its own,
this allows the same Enum value names to be used in different enums. For example, the
.kcfg entry

\code{.xml}
<entry name="KeepData" type="Enum">
  <choices>
    <choice name="Do">
    <choice name="Dont" value="Don't">
  </choices>
</entry>
\endcode

will generate this public class containing the enum definition, inside the generated class:

\code{.cpp}
class EnumKeepData
{
  public:
  enum type { Do, Dont, COUNT };
};
\endcode

Since 5.68, if present the <b>value</b> attribute will be used as the choice value written to the backend
instead of the <b>name</b>, allowing to write text incompatible with enum naming.

Alternatively, if <b>GlobalEnums</b> is set to true, all Enum items are defined as
unnamed enums in the global scope of the generated class. In this case, all Enum values
must have different names to avoid clashes. However, you can use a 'prefix' argument
in \<choices\> to prevent duplicate enum member names clashing. Using this, the Enum value
names are prefixed in code with the string you specify. For example, if <b>GlobalEnums</b>
is set to true, the .kcfg entry

\code{.xml}
<entry name="KeepData" type="Enum">
  <choices prefix="Keep_">
    <choice name="Do">
    <choice name="Dont" value="Don't">
  </choices>
</entry>
\endcode

will generate config file entries of "KeepData=Do" and "KeepData=Dont", but the enum
will be declared

\code{.cpp}
enum { Keep_Do, Keep_Dont };
\endcode

It is possible to specify your own name for a generated enum, by including a
'name' parameter in \<choices\>. Just like unnamed enums, this enum will be defined in
the global scope of the generated class (without any enclosing class of its own).
Therefore the names of Enum values must be unique across both unnamed enums (if
<b>GlobalEnums</b> is set to true) and all specifically named enums.

An example of a specifically named enum:

\code{.xml}
<entry name="KeepData" type="Enum">
  <choices name="Types">
    <choice name="Do">
    <choice name="Dont">
  </choices>
</entry>
\endcode

which results in the following enum declaration, inside the generated class:

\code{.cpp}
enum Types { Do, Dont };
\endcode

It is also possible to specify the use of enums external to the generated class, by
including the string "::" in the enum name - just ensure that it is sufficiently
qualified to be unambiguous in use. To specify use of an unnamed enum, append a
trailing "::". For example, to use the enum 'myEnum' defined in class ClassA, use
either of

\code{.xml}
<choices name="ClassA::myEnum">
<choices name="::ClassA::myEnum">
\endcode

To specify an unnamed enum in namespace ProgSpace, use

\code{.xml}
<choices name="ProgSpace::">
\endcode

To specify a top-level unnamed enum, use

\code{.xml}
<choices name="::">
\endcode

To specify the top-level enum 'anotherEnum', use

\code{.xml}

<choices name="::anotherEnum">
\endcode


\subsection notify_signals Notify signals

An entry can emit a signal when it gets changed. First of all, you must
define a list of signals for the configuration class. The signal's name may be
any legal identifier you wish. The \<argument\> tag allows you to specify arguments
for the emitted signal. It supports all types as defined in
the KConfigXT DTD. The argument value must specify the name, without spaces, of one
of the entries defined in the .kcfg file.
A signal definition can also contain a \<label\> tag which will be
the documentation line in the generated file.

\code{.xml}
<signal name="emoticonSettingsChanged" />

<signal name="styleChanged">
  <label>Tell when a complete style change.</label>
  <argument type="String">stylePath</argument>
  <argument type="String">StyleCSSVariant</argument>
</signal>
\endcode

After defining the signals, you must tell which signal to emit for the entry.
A signal can be emitted by multiple entries. Also, you don't need to specify the arguments
for a signal, the signal name will suffice.

\code{.xml}
<entry key="stylePath" type="String">
  <label>Absolute path to a directory containing a Adium/Kopete chat window style.</label>
  <emit signal="styleChanged" />
</entry>
\endcode

You can also use the generic configChanged() signal from KConfigSkeleton to notify your application
about configuration changes.

\subsection translation_context Translation context

In the kcfg file you can specify the translation's context for \<tooltip\>, \<whatsthis\> and \<label\> element for an entry.

\code{.xml}
<entry type="Bool" key="Auto Save">
  <label>Enable automatic saving of calendar</label>
  <whatsthis context="@info:whatsthis">Enable automatic saving of calendars to have calendars saved automatically.</whatsthis>
  <default>false</default>
</entry>
\endcode

For more information on translation context and how to write good translatable text,
please refer to https://api.kde.org/frameworks/ki18n/html/prg_guide.html

*/