Tag Archives: bindings

Why KDE bindings simply rock (or: Creating our first Ruby plugin for Kate)

Akademy really speeds up development and communication between developers:
Yesterday I was poked by Milian Wolff and he told me how many people want to write Kate plugins in languages other than C++ and ECMAScript and how he always told them that’s not possible and probably a huge amount of work to get working. Well, that wasn’t entirely true:
If the target application has a SMOKE lib that wraps its API and an according bindings extensions, it works pretty much out of the box, thanks to the gorgeous KPluginFactory API and of course thanks to our gorgeous bindings.
Kate was a bit trickier to get working though, because it used old and deprecated API to load plugins. Well, I filed a merge request on gitorious about that, fixed a bug in KRubyPluginFactory and now I’m very proud to present

The absolutely gorgeous, simple, straight-forward, packed with all the Ruby goodness, very first Ruby Hello-World Kate plugin:

require 'kate'

# The module name has to be the capitalized name of the containing directory.
# In this case, the directory name is kate_ruby_test, so the module name _has_
# to be KateRubyTest.
module KateRubyTest

  # The main class name is the capitalized name of the main script. In this case it's 'test.rb',
  # so the main class name is 'Test'.
  class Test < Kate::Plugin

    # initializer
    def initialize parent, args = nil
      # call Kate::Plugin's constructor
      super parent, 'kate-ruby-hello-world'

    def createView mainWindow
      # @componentData is automatically set to the plugin's component data after the constructor has run
      return KateRubyHelloWorldView.new mainWindow, @componentData


  class KateRubyHelloWorldView < Kate::PluginView
    slots 'slotInsertHello()'

    def initialize mainWindow, componentData
      super mainWindow

      # create the action defined in the ui.rc file
      @guiClient = Kate::XMLGUIClient.new componentData
      action = @guiClient.actionCollection.addAction('edit_insert_helloworld')
      action.text = KDE::i18n('Insert Hello World')
      connect action, SIGNAL('triggered(bool)'), self, SLOT('slotInsertHello()')

      # and add our client to the gui factory
      mainWindow.guiFactory.addClient @guiClient

    def slotInsertHello
      return if self.mainWindow.nil?

      kv = self.mainWindow.activeView

      kv.insertText 'Hello World!' if !kv.nil?

    def readSessionConfig config, groupPrefix
      # do something useful here

    def writeSessionConfig config, groupPrefix
      # do something useful here



You’ll also need an ui.rc file that defines the actions to be merged into the Kate main window and a .desktop file which describes your plugin. Actually I’m too lazy to post them all here, so I made a nice package containing everything you need, together with a Makefile which can ‘make install’ the plugin into your home directory.

Since all SMOKE based bindings wrap the C++ API nearly 1:1 and only add syntactic language specific sugar on top, you can create nearly any plugin you like in any language, without modifying the host application, as long as the API is wrapped in a SMOKE lib and a bindings extension. In C# you can even create KIO slaves (a monodoc KIO slave example is shipped with the kdebindings tarball). That feature hasn’t been added to Ruby yet, but is on my ToDo list.

So praise the bindings, praise the KDE plugin infrastructure and start working on Ruby Kate plugins! 🙂

You can find the Ruby Kate binding and the SMOKE kate lib in current kdebindings trunk.

qyotoassemblygen progress

Some time back I have started a tool called qyotoassemblygen [0], which will hopefully ease the generation of .NET/Mono bindings based on SMOKE libraries. It basically introspects a SMOKE library and generates a System.CodeDom tree from that information. The CodeDom can then be used to generate C# code and/or compile an assembly.
Although some parts were rather difficult and had to be rewritten again and again (like checking whether a method has to be marked “override” or “virtual”), I can now announce that it”s quite stable and generates all of the Qt assemblies just fine :). I”m currently working on getting the KDE assemblies to build, which is really just a matter of sorting out *Private classes.

By using plugins the tool is not bound to Qt-based bindings, so we could as well generate assemblies for other toolkits, like Wt (for which there is already a smoke lib, thanks to Richard :)). Plugins will also make it easy to add syntactic sugar like event support for Qyoto (which I hope I can implement for KDE SC 4.5).

If everything works as expected, we can hopefully drop kalyptus completely in the next release and reduce our maintenance cost considerably 🙂

[0] http://websvn.kde.org/trunk/playground/bindings/qyotoassemblygen

gsoc, week 11 – generating smokekde :)

Now that the Qt classes generate and compile fine (as Richard already wrote) I tried to generate the smokekde sources with the new generator last week.

After fixing quite a bunch of bugs that didn”t surface when generating smokeqt, it works now really well.
There isn”t much difference between the config files for qt and kde, too – it”s mainly the lists of stuff to include and very little stuff to be excluded (d pointers, q pointers, other private stuff…).
This really shows that the new parser is superior to kalyptus, which had dozens of hacks in it for the code to generate nicely.

In case you want to test it, get the source from /trunk/playground/bindings/smokegenerator. To make testing easier, I wrapped the generation in cmake, so a normal cmake; make; make install should build and install smokeqt and smokekde for you.

The new generator still generates a lot of code for deprecated methods, which isn”t really nice – but maybe the parser can be modified so it recognizes __attribute__((deprecated)) flags.
There are also still issues with fixed-width array types, which luckily don”t occur too often in KDE sources. This only affects KMD5 for the moment. I”ll fix this next week, so then should smokekde with smokegenerator be equal to smokekde with kalyptus 🙂

Hello Planet!


my name is Arno Rehn and I”m a bindings developer. I”m working mainly on the C# bindings for Qt and KDE together with Richard Dale.

Currently I”m also working on my gsoc project – Rewriting the SMOKE generator using one of Roberto Raggi”s C++ parsers.
SMOKE is a library which provides the possibility to dynamically call methods on classes. It is the foundation for many of the Qt/KDE bindings, like Ruby, C# and PHP.
The old generator for the SMOKE sources is based on a perl tool, kalyptus, and only works with a bunch of hacks in the code. It tends to break on new releases of Qt or KDE which introduce new features.

The goal of my project is to create a stable and robust tool, similar to the moc, which you just run on the headers of your project and you then end up with a bunch of source files that are the basis for bindings for your project.

Eventually I decided to use the new parser from KDevelop4, since that has a pretty convenient API (unlike the QtJambi / qtscriptgenerator one). It took some time to remove the KDevPlatform/KDevelop specific bits, though. It would”ve also been nice if I could”ve used the DUChain from KDevelop, but that seems to be so tightly integrated that I would have to provide half of KDevelop to use it.

I”m pretty much ahead of time – the generator is nearly finished. By the end of the GCDS, which I”m attending until Thursday, it should be working completely – at least with the Qt classes.

P.S.: I know that gsoc has started quite some time back, but I was really to lazy/busy to start a blog 😉