KDevelop5/File template specification

 

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Template language

Source filj templates use the Grantlee library for rendering templates. It has more features than KMacroExpander, the most important being loops and the ability to expose custom data types from C++ code to templates. The use of Grantlee makes templates more powerful, but also more difficult to write.

For information regarding Grantlee templates in general, refer to its documentation. Since Grantlee's template language is based on Django's, it might be useful to read the Django template documentation as well.

Example template template

There is a project template that creates a new project consisting of a single KDevelop class template. You can use it by starting a new project, choosing Get More Templates... and installing this one. Proceeding to create a project using this template will create an example class template.

File structure

Like project templates, file templates are compressed directories, and they too contain a special description file and any number of content files. It is recommended that the description file has a .desktop extension instead of .kdevtemplate, although both are supported.

Unlike with project templates, not all files from the archive are copied to the output directory. Because Grantlee supports template inheritance and inclusions, file templates may contain helper files that only serve for convenience and produce no actual output. The actual output files have to be specified in the template description.

Description file format

The template descriptions files are normal .desktop files. They must contain a General section, as well as one section for each output file. In most cases, the template will have two output files for C++ classes and one output file for other languages. However, using separate user interface files and/or a shared d-pointer hierarchy can cause a class to need more files. Templates in KDevelop allow any number of output files.

Example

An example description for a template with three output files is below

[General]
Name=Private Pointer
Comment=C++ Class with a private D-pointer
Category=Class/C++/Basic
Files=Header,PrivateHeader,Implementation
OptionsFile=options.kcfg

[Header]
Name=Public Header
File=class.h
OutputFile={{ name }}.h

[PrivateHeader]
Name=Private Header
File=class_p.h
OutputFile={{ name }}_p.h

[Implementation]
Name=Implementation
File=class.cpp
OutputFile={{ name }}.cpp

Entries

The Name and Comment entries are the same as in other .desktop files and can be translated. The Category is used for grouping when showing a list of templates to the user. It can contain more than one level, separated by slashes. The first level must be the template type, either Class or Test. Templates with other type can be used, but classes and tests receive some additional configuration and variables. It is recommended that the second level is the language name, and the third the framework name.

The OptionsFile entry is optional, using it specifies configuration options for this template. For more information about template options, see Custom options.

Output files

The Files entry specifies template output files. It is a list of strings, where each element is the same as a name of a group in the description file. The corresponding group has three required entries

• Name is the user visible file name. It can be translated.
• File is the path to the input file within the template archive
• OutputFile is the suggested output file name. The actual name can be set by the user, but this is the default value. It will be converted to lowercase if needed, so don't do in here.

The description file above results in a dialog page such as this

Assistant page for template output files

Variables

The following variables are passed to all templates, regardless of their type

Variable name	Type	Description	Example value
license	String	The license header without any comment characters. It can be split into multiple lines.	One of the headers listed in KDE Licensing Policy
output_file_foo	String	The relative path to the output file with identifier foo	mynewclass.h
output_file_foo_absolute	String	The absolute path to the output file foo	/home/user/projects/myproject/mynewclass.h

Additionally, values of any template options exposed by the template are passed as variables.

The following variables are passed to Class templates

Variable name	Type	Description	Example value
name	String	Class name without namespaces	Example
identifier	String	The full identifier of the new class, which is composed of namespaces and class name	MyProject::Utilities::Example
namespaces	StringList	List of nested namespaces in which the class is declared	[MyProject, Utilities]
description	ClassDescription	An object containing the class name, base classes, functions and members
baseClasses	InheritanceDescriptionList	All direct base classes of the new class, containing both the inheritance type and the base class name.
functions	FunctionDescriptionList	List of all the functions in the new class
members	VariableDescriptionList	List of all the member variables in the new class

The variables which are passed to class templates are also described in the API documentation.

Additional templates and filters

To make writing templates easier, KDevelop supplies additional template utilities. They are both in the form of text template, available for including into your own, or additional Grantlee filters.

Templates for inclusion

These templates usually read some variables from the context. Thus, you have to make sure the correct variables are set before including the template. This is normally done using with statements.

{% for f in functions %}
  {% with f.arguments as arguments %}
    {{ f.returnType|default:"void" }} {{ f.name }}({% include "arguments_types_names.txt" %});
  {% endwith %}
{% endfor %}

Includable templates in KDevPlatform are:

Template	Required variables	Language	Description
arguments_names.txt	arguments : VariableDescriptionList	Weakly-typed languages	Comma-separated list of argument names.
arguments_types_names.txt	arguments : VariableDescriptionList	Strongly-typed languages	Comma-separated list of argument types and names.
include_guard_cpp.txt	namespaces : StringList	C++	Include guard macro, generated from the namespaces and the class name.
namespace_open_cpp.txt	namespaces : StringList	C++	Opening tag for nested namespaces
namespace_close_cpp.txt	namespaces : StringList	C++	Closing tag for nested namespaces
namespace_use_cpp.txt	namespaces : StringList	C++	using namespace statement for nested namespaces

Template filters

KDevPlatform provides an additional filter library. Because filters are implemented in code and not modifiable by users, it is preferred to use template inclusion if possible. These filters are mostly utilities for string operations and are not language specific.

To use them in templates, add {% load kdev_filters %} to the beginning of your template file.

Template filter	Description
lines_prepend	Takes a string argument and prepends it to every line of the input. It is intended for licenses and other blocks of commented text.
upper_first	Converts the first character of input into uppercase, and leaves the rest intact. This is useful for creating accessor functions, and prefixing identifier in general.
camel_case	Converts the input from an underscore notation to camel case, starting with a lowercase character.
camel_case_upper	Converts the input from an underscore notation to camel case, starting with an uppercase character.
underscores	Converts the input to the underscore notations, where words are separated by underscores instead of uppercase letters. The output is entirely lowercase.

Custom options

Templates can expose configuration options to the user prior to the class generation. To do this, add a KConfig XT formatted file into the archive, and specify an OptionsFile entry in the template description file pointing to it.

OptionsFile=options.kcfg

Note

Template options are meant to be used only for small differences in large, complex templates. To reduce the number of necessary clicks, it is preferred to use separate templates instead.

For information about the options file format, see Using KConfig XT. Note that KDevelop only supports a subset of the KConfig XT specification. Only Int, Bool and String types are recognized, options with other types are ignored. Furthermore, only name, type, label and default attributes are used. The default value of options is rendered as a template, so it can include variables.

Here is an example options file that exposes two string options, useful for private pointers

<?xml version="1.0" encoding="UTF-8"?>
<kcfg xmlns="http://www.kde.org/standards/kcfg/1.0"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.kde.org/standards/kcfg/1.0
      http://www.kde.org/standards/kcfg/1.0/kcfg.xsd">
  <kcfgfile arg="true"/>
  <group name="Private Class">
    <entry name="private_class_name" type="String">
      <label>Private class name</label>
      <default>{{ name }}Private</default>
    </entry>
    <entry name="private_member_name" type="String">
      <label>Private member name</label>
      <default>d</default>
    </entry>
  </group>
</kcfg>

Just before creating the class, KDevelop will show an assistant dialog page, asking for the two options

Assistant page for template options

The values the user sets for the two options will be available to the template as variables with names matching the entry names. In the private pointer example, the d-pointer declaration template might look like this

private:
    {{ private_class_name }}* const {{ private_member_name }};

If the user accepts the default values, and the class name is Example, the rendered result of this snippet will be

private:
    ExamplePrivate* const d;