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.

XML description of the configuration options

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

The <kcfgfile> tag contains the name of the configuration file described. Omitting the name will make the generated class use the default configuration file ("<appname>rc").

The <include> tags are optional and may contain C++ header files that are needed to compile the code needed to compute default values.

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 name is used to create accessor and modifier functions. It's also used as the key in the config file. If <key> is given, but not <name>, the name is constructed by removing all spaces from <key>.

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 type the following special types are supported:

• Path 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.

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

• IntList This indicates a list of integers. This information is provided to the application as QValueList<int>. Useful for storing QSplitter geometries.

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 so that the code which computes the default value can be compiled.

Additional code for computing default values can be provided 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.

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:

Name	Type	Default	Description
File	string	programname.kcfg	Name of kcfg file containing the options the class is generated for
NameSpace	string	-	Optional namespace for generated class
ClassName	string	-	Name of generated class (required)
Inherits	string	KConfigSkeleton	Class the generated class inherits from. This class must inherit KConfigSkeleton.
Visibility	string	-	Inserts visibility directive (for example KDE_EXPORT) between "class" keyword and class name in header file
Singleton	bool	false	Generated class is a singleton.
CustomAdditions	bool	-
MemberVariables	string: public|protected|private	private	C++ access modifier used for memeber variables holding the configuration valuse
IncludeFiles	comma separated list of strings	-	Names of files to be included in the header of the generated class
Mutators	true, false or a comma seperated list of options	-	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.
ItemAccessors	bool	false	Generate accessor functions for the KConfigSkeletonItem objects corresponding to the configuration options. If SetUserTexts is set, ItemAccessors also has to be set.
SetUserTexts	bool	false	Set the label and whatthis texts of the items from the kcfg file.If SetUserTexts is set, ItemAccessors also has to be set.
GlobalEnums	bool	false	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 will get an own namespace for its choices.

Advanced options

There are several possibilities to parameterize 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:

  <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>

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

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

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:

  <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>

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

sound_Explosion=boom.wav sound_Crash=crash.wav sound_Missile=missile.wav

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.

• Parameterized groups

...STILL TODO...

If you have questions or comments please contact Cornelius Schumacher <schumacher@kde.org> or Waldo Bastian <bastian@kde.org>