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» Kate/KDevelop Sprint 2014: Let There Be Clang

Mon, 02/03/2014 - 23:58

Time flies… The extremely productive hack sprint at the friendly Blue Systems office in Barcelona is over for more than a week. I haven’t had time to blog about the last days yet which I hereby make good for!

I spent a lot of time at the sprint polishing the KDevelop Clang plugin. A up-to-now semi-secretly developed language plugin based on clang which will replace our current C++ language support in KDevelop in the long-run.

» KDevelop 4.3.0 - Go Get It!

Tue, 03/20/2012 - 13:21

Finally I managed to get my job as the release dude done: http://kdevelop.org/kdevelop/kdevelop-430-final-released-basic-c11-support

Thanks to all the developers who sent in patches! The same goes to our loyal users for their continued support and bug reports :)

It’s really fun to work on KDevelop and - I’ve said it many times before - I’m really looking forward to our next releases! Even now our code in the master branches has some neat commits that make the eventual 4.4 release something to look forward to!

» GSOC: C++2011 Support in KDevelop Part 1

Tue, 06/28/2011 - 14:09

Hey all,

I finally want to write a bit about my work on KDevelop during this year’s GSOC. To make things a bit more interesting for the whole crowd, even for those heretics that don’t use KDevelop, I want to highlight some C++2011 features I got to know in the process. Hence this multipart blog post should be interesting for all KDE hackers, as eventually we will be able to use these shiny new features of what is to be known as C++2011.

For those interested in the full overview of changes in C++2011, take a look at e.g. the C++0x Status Page in GCC 4.6, the wikipedia article on C++0x, or try to get hold of a copy of the C++2011 FDIS spec file. Note that the latter is apparently not freely accessible, see also this stackoverflow discussion. Still, maybe you find someone who can send you a copy…

So, lets get down to business. Following is a not-complete list of C++2011 features I’ve already implemented in KDevelop. If I mess something up in explaining a new feature, or if I forget an important aspect, please add a comment.

Range-Based for

This neat little addition is not so important to most Qt developers. We know and love our foreach macro. C++2011 comes with a similar built-in construct called range-based for. Essentially the syntax goes like this:

  1. QVector<MyType> list;
  2. for(const MyType& item : list) {
  3. // do stuff
  4. }

It’s neat, and very similar in syntax to the oldschool foreach macro. But there is a big difference: Where foreach makes a copy of the container, range-based for does not. This has mainly two implications:

  1. foreach is slow when used with containers that don’t use implicit sharing, most prominently STL containers
  2. range-based for has undefined behavior when you change the list you iterate over inside the loop.

Personally, I think I’ll stick to the foreach macro as it’s known to work well and has no big downsides in most Qt-based applications, as implicit-sharing is widely used throughout Qt.

RValue References / Move Support

This feature is a more advanced topic and mainly interesting for library developers who want to implement move semantics and/or achieve perfect forwarding, resulting in much better performance under certain conditions. Take a look at the Brief Introduction to RValue References, or the associated spec changes. From the syntax POV it’s just a matter of using && for rvalue references compared to the single & for normal lvalue references.

Defaulted and Deleted functions

This addition to the C++ spec is very welcome to me as it makes some code much more readable and also can be used to prevent hard-to-debug bugs or to improve performance. I’m talking about defaulted and deleted functions. E.g. from the wikipedia article:

  1. struct NonCopyable {
  2. NonCopyable & operator=(const NonCopyable&) = delete;
  3. NonCopyable(const NonCopyable&) = delete;
  4. NonCopyable() = default;
  5. };
  6. struct NoInt {
  7. void f(double i);
  8. void f(int) = delete;
  9. };

This shows the syntax of how to use this new feature. The advantages:

  • You can explicitly mark functions as deleted: Before you had to move these functions into private section of a class and not provide an implementation. When (accidentally) trying to use such a function you used to get unintuitive compile or linker errors. Now you get a nice message about usage of an explicitly deleted function.
  • You can prevent unwanted conversions: Using deleted functions is also useful when you want to prevent some function to be called with a different type that can be implicitly converted to your function’s wanted argument type.
  • Performance with defaulted functions: Compilers tend to write highly optimized code where possible. Implicitly defined constructors or assignment operators e.g. are one of these cases. But as soon as you use inheritance you (mostly) cannot use the implicit versions. Thanks to the new defaulted functions you can do that again. Furthermore it’s possible to change the access policy of an implicitly defined function (which are usually public) using the default syntax.
Variadic Templates

I confess that this is one of the more esoteric features of C++2011 for me. I never really did any serious template meta programming, and variadic templates are just as complicated as the other template programming. Yet I do see the advantages if people start to use it.

Anyhow, I implemented the required parser changes into KDevelop, but proper code completion and DUChain integration might need some time and brain effort :)


Now back to simpler things, yet definitely welcome and useful ones. One example are static assertions, i.e. compile-time assertions. The document I linked to contains a list of examples which should show how useful this feature is. Note that we Qt-users know and love the Q_ASSERT macro, but it is a runtime check. Boost users have had a BOOST_STATIC_ASSERT macro for some time, now we will finally be able to use it as well.

STL updates

Ah, before I forget it: Since KDevelop parses the STL includes, you should be able to use all new STL features already. If you spot a serious parser error in one of the include files of GCC 4.6 or 4.7, please notify me.

much much more

These are only some of the new features which I’ve added support for in KDevelop. I’ll try to sit down later today to write part 2, otherwise I’ll do that after I come back from the Fusion festival next week. Anyways, you can stay tuned for features like constexpr, opaque-enum-declarations, class-enums, improved right-shift token handling in nested templates, etc. pp.

» KDevelop: Randa and GSOC 2011

Thu, 06/09/2011 - 15:59

Yawn. Hello everyone!

After two nights of backporting sleep in my RL branch to fix the deficiency I built up during Randa, I feel somewhat normal again. Time to blog, eh?


Lets begin with Randa. It was not only my first time there, but also my first time ever to be in the Swiss Alps. And furthermore it was the first time for me to be in the Alps without crying out loud about the lack of snow as I didn’t intend to go snowboarding. You can imagine it was a very pleasant experience for me. I definitely want to come back to go on some more serious hiking trips uphill. But I diverge ;-)

Randa as place for a sprint was simply awesome: Secluded hence no real distractions. Great environment to clean your head, get fresh air and stay focused and productive. Good food, nice people, … I could go on here :) The only negative things I noticed where the unstable networking and the dormitories.

KDevelop Sprint

The KDevelop sprint at Randa was very successful and productive. Here is a group picture of those who attended:

Randa 2011 KDevelop Group Picture
KDevelop Hackers at Randa 2011

from left to right: Sven Brauch (Python Support), Laszlo Papp (Gluon), Milian Wolff (…), Niko Sams (PHP, GDB, …), Aleix Pol (CMake, …), Alexander Dymo (UI, Ruby, …)

Aleix already blogged about what he did, so I won’t reiterate that. Instead let me point you to the incomplete log of our discussions on Techbase. Here are my personal highlights of the sprint:

  • We/I will setup a continous/nightly build- and regression-testing machine for KDevplatform/KDevelop and related plugins. Thanks already for the kind offers for hosting. More on this later
  • some more plugins from e.g. Quanta will see a released soon. Due to lack of manpower we cannot wait for a stable Quanta release, but some plugins in there are already stable and usable.
  • we will have some “welcome to kdevelop” page eventually, based on Aleix’s work with the Plasma Dashboard
  • Niko’s “Browser Like Tabs” mode will be merged eventually, try it out now and give us feedback!
  • Alexander merged a partial rewrite of the UI framework in KDevelop, bringing lots of new features and less bugs as well as reducing our codebase!
  • Sven attended his first KDE sprint and continued to work on a kick-ass python language support for KDevelop! Rock on!

I could go on and on here, we really did lots of stuff. It was great meeting you all again, hope to see you soon (at the Desktop Summit?).


To finish this already long blog off, here a few notes on my GSOC. As you might have heard, I work on bringing C++2011 (aka C++0x) support to KDevelop. I’ve already pushed some changes to my branch which adapt our parser to support the range-based for loop syntax as well as RValue references and variadic templates. Proper DUChain integration is pending, yet it already makes working with C++2011 features much more bearable! Stay tuned for a more in-depth report.

» KDevelop Hack Sprint 2009 - Day 2 and 3

Thu, 04/23/2009 - 01:31

Ok, just a quick update on what we are doing / have done the last two days except drinking beer and eating quite a lot of food (though it never seems to be enough somehow….)

  • Apol was polishing CMake support, speeding up KDevelop startup time when you enabled the QtHelp plugin, making sure that Kross plugins get loaded properly and some other things
  • Adymo started some refactoring of Sublime in an experimental branch (actually they had quite a long discussion right now about things in the UI which should be changed/fixed). Besides that he also fixed some little bugs in the includepath resolver for CMake
  • Nsams is fixing PHP support and adding new features here and there. Esp. completion inside a foreach over a Iterator class works now!
  • and as always ZWabel did fix quite a lot of bugs, most of them which only were discoverable in a few corner cases, very nice indeed.
  • shaforo who sadly already left us again to attend university fixed the sorting in the Project view among other things
  • With Apols help I managed to get started with a documentation plugin which (currently) integrates PHP.net. I plan to make it possible to use the downloadable PHP.net documentation as well to speed things up. Actually setting up a documentation plugin is very easy! Maybe I’ll take a look at writing a documentation plugin for Zend, Symfony, etc. pp. as well - should be fairly easy. Maybe I can come up with a generic documentation plugin which makes it possible to include any kind of .html documentation with some configurable mapping… lets see! Or maybe I should take a look at writing Kross plugins (Apol could help me here as well) for that purpose.

Except these changes we also discussed how to support dynamically typed languages like PHP, Ruby, Python and JavaScript better. One result of it that we now plan to fully support the dedicated map types of each language, with autocompletion and such. Of course that won’t be possible for 100% of the use-cases, but we hope to support at least the most common ones (i.e. 90%). You can take a look at http://www.kdevelop.org/mediawiki/index.php/SupportForDynamicMaps for more information.

Additionally Nsams, Apol and Zwabel took a look at the GDB plugin and started working on it a bit. It’s still a work in progress though.

My biggest change is that color highlighting support for dark color schemes now is in trunk. It automatically adapts to changes in the global KDE color scheme, yet you still have to manually change the Kate color scheme. Actually I intend to add an interface to Kate so we can use it’s color schemes instead of the global KDE one - makes much more sense and would fix some bugs (i.e. fix from dark color scheme to a light one). Here’s a screenshot of it (with the PHP.net documentation showing):

highlighting in kdevelop with dark color scheme
dark color scheme and syntax highlighting in KDevelop 4

If you followed the planet kde you might have seen some blog posts about color reception and color generation by Ariya Hidayat. I will take a look at it and implement it in KDevelop. Or I simply pick a given set of colors and use them - for 10 colors or so we need it doesn’t make that much sense to let them be generated. Yet the article he linked to about adaptive coloring for syntax highlighting will be helpful I think! Thanks!

Yet it currently works quite well I’ll first try to fix the colors in the Declaration tooltip, quickopen and codecompletion lists.

So stay tuned for more KDevelop goodness throughout the next days.

» PHP support for KDevelop 4 (and eventually Quanta+)

Tue, 03/03/2009 - 00:28

Hello Planet KDE!

I want to give you a little insight on the current state of PHP support in KDevelop4:

Me and Nikolaus Sams (nsams) are working diligently on a plugin for PHP support in playground. It’s somewhat stable, i.e. we fix any crashes we stumble upon, but I would call it Alpha state at most. It may eat your babies so to speak. Yet I’m happy to say that at least one user is already using it for production (hi leinir ;-) ).

implemented PHP support

Well, here’s a (not complete) list of features that are already working. Though I have to warn you: no screenshots included ;-) It’s actually all very similar to the C++ screenies you can see on the web.

sematic highlighting

Let’s start with a feature that only very recently was added for PHP - semantic highlighting. Niko moved some language independent parts of the C++ plugin from KDevelop to KDevplatform and now PHP has the same code highlighting features as C++.

I personally love this feature since it makes it even easier to grasp code and it makes the code highlighting more consistent since there is no visual difference between PHP built-in functions/constants and your own.

code completion

Arguably one of the most useful features the DUChain enables us to write is code completion. There’s already full support for:

  • PHP built-in functions, classes, constants, superglobals
  • user-defined functions, classes, constants, superglobals, variables, etc.
  • proper code completion for objects which respects access modifiers (private, public, protected) and differentiates between static/non-static members and methods
  • code completion for overridable and implementable functions inside classes
  • hints in the argument list of function- and method class
  • sane code completion after keywords such as “extends, implements, catch(), new, throw” and some more I think

There’s still some bugs to fix and a few features to implement. But I can easily say that even the current state of code completion makes one wonder how he could use Quanta (from KDE3 times) for such a long time! It’s simply nothing compared to this!

The next feature I hope to add is support for type hinting in function calls. I.e. only show arrays where arrays are requested and the same for objects of a given type. Also no PHP keywords are currently completed at all

other DUChain/UseBuilder stuff

Thanks to the DUChain you already get lots of information about declarations, such as uses (which files, which lines etc.). Also very neat is the hover popup you might now from C++ which among others shows you phpdoc comments inside your browser. I also plan to integrate the php.net documentation into KDevelop, similar to what is already possible for QtHelp.

inline validation / syntax checking / linting

Another feature which saves lots of time is on-the-fly syntax checking: You won’t have to fire up your web-app inside a browser just to be greated by that pesty “syntax error, unexpected ‘CHAR’ in FILE on line XYZ” message… No! Instead you will see a nice reddish zig-zag line where you made the error and can fix it before heading off to the browser.

But we don’t only do basic syntax checking. We do more than that, thanks again to the power of the (holy?) DUChain. You can spot undeclared variables, function/method/class/constant redeclarations and more. Actually I hope that one day we spot most of the notices, warnings and errors PHP could emit.


We already have a multitude of regression tests which will make sure that we don’t mess up any existing stuff. Lets hope for even more of them :) I love test-driven development.

The End

Well, thats pretty much it for the moment. You can have a look at what we are up to at the Quanta Feature plan on techbase.

If you are a PHP developer and can write C++ with Qt, why not get in touch with us? You can find us both on the KDevelop mailinglist and at least me and leinir are often found in #kdevelop on freenode.


Let me finish with a quick introduction of myself:

My name is Milian Wolff, I study Physics at the FU Berlin (just finished the 3rd semester). I started learning programming when I was around 14 with PHP. Over the years I became very good in it and the other webdevelopment techniques like Css, JavaScript etc. Recently I started to fullfill my biggest geek dream by learning C++/Qt/KDE and starting to contribute to the KDE project.

Some of you might now my from the LinuxTag in Berlin where I could be found at the Kubuntu-De.org community booth. At least with some of you I had a beer (well, I doubt it was only one). I hope to repeat this tradition in 2009. Every once in a while I can also be spotted at ubuntu-berlin events.

» Patching Kirocker Music Display for volume control via mouse scrolling

Fri, 03/28/2008 - 16:32

Kirocker is such a great application, it’s a pity the developer Sébastien Laoût has given up on it and is using Windows now!

Usually I only use the kicker applet, the full screen window is nice for parties though. But I didn’t like the way the applet handles scroll events: It seeks (if possible). Since I rarely seek when listening to music I’d rather have the behaviour of the Amarok tray icon: volume control!

I had a look inside the sources and found this part in src/coverdisplay.cpp:

  1. void CoverDisplay::wheelEvent(QWheelEvent *event)
  2. {
  3. if (areControlsShown()) {
  4. if (event->orientation() == Qt::Vertical) {
  5. PlayerInformation *infos = PlayerInformation::instance();
  6. if (infos->canSeek()) {
  7. int deltaSeconds = 10 * (event->delta() > 0 ? 1 : -1);
  8. m_infos->seekRelative(deltaSeconds);
  9. }
  10. } else {
  11. if (event->delta() > 0)
  12. AmarokApi::volumeUp();
  13. else
  14. AmarokApi::volumeDown();
  15. }
  16. }
  17. }

As you can see it already supports volume control via scrolling! The thing is I’ve disable four-way scrolling for my MX1000. Thus I’ve simply swapped the if statements and now I’m really happy with Kirocker. Here’s the updated snippet:

  1. void CoverDisplay::wheelEvent(QWheelEvent *event)
  2. {
  3. if (areControlsShown()) {
  4. if (event->orientation() == Qt::Vertical) {
  5. if (event->delta() > 0)
  6. AmarokApi::volumeUp();
  7. else
  8. AmarokApi::volumeDown();
  9. } else {
  10. PlayerInformation *infos = PlayerInformation::instance();
  11. if (infos->canSeek()) {
  12. int deltaSeconds = 10 * (event->delta() > 0 ? 1 : -1);
  13. m_infos->seekRelative(deltaSeconds);
  14. }
  15. }
  16. }
  17. }

Replace the old code, compile Kirocker, install it. Then restart kicker (killall kicker; sleep 1; kicker;) and Kirocker should accept scroll events in the way the Amarok tray icon does!