Post Akademy

So, it has been a busy week of Qt and KDE hacking in the beautiful city of Vienna.
Besides getting quite some of the Viennese staple food, schnitzel, it was an interesting adventure of getting smarter.

  • Getting smarter about making sure what happens in North Korea doesn’t stay in North Korea
  • Getting smarter about what is up with this newfangled Wayland technology and how KDE uses it
  • Getting smarter about how to Konquer the world and welcoming new contributors
  • Getting smarter about opensource licensing compliance
  • Getting smarter about KItinerary, the opensource travel assistant
  • Getting smarter about TNEF, a invitation transport format that isn’t that neutral
  • Getting smarter about Yocto, automotive and what KDE can do

And lots of other stuff.

Besides getting smarter, also getting to talk to people about what they do and to write some patches are important events.
I also wrote some code. Here is a highlight:

And a lot of other minor things, including handling a couple of Debian bugs.

What I’m hoping to either put to my own todolist, or preferably others, is

I felt productive, welcome and … ready to sleep for a week.

Invite me to your meetings

I was invited by my boss to a dinner. He uses exchange or outlook365 or something like that. The KMail TNEF parser didn’t succeed in parsing all the info, so I’m kind of trying to fix it.

But I need test data. From Exchange or outlook or outlook365. That I can add to the repoository for unit tests.

So if you can help me generate test data, please setup a meeting and invite me.

Just to repeat. The data will be made public.

The smart button

I don’t always understand why people do things in some ways.

80bit x87 FPU

Once again, I got surprised by the 80 bit x87 FPU stuff.

First time was around a decade ago. Back then, it was something along the lines of a sort function like:

With some values, first and would be smaller than second, and second smaller than first. All depending on which one got truncated to 64 bit, and which one came directly from the 80bit fpu.

This time, the 80 bit version when cast to integers was 1 smaller than the 64 bit version.

Oh. The joys of x86 CPU’s.

Partially initialized objects

I found this construct some time ago. It took some reading to understand why it worked. I’m still not sure if it is actually legal, or just works only because m_derivedData is not accessed in Base::Base.

Kirigaming – Kolorfill

Last time, I was doing a recipe manager. This time I’ve been doing a game with javascript and QtQuick, and for the first time dipping my feet into the Kirigami framework.

I’ve named the game Kolorfill, because it is about filling colors. It looks like this:


The end goal is to make the board into one color in as few steps as possible. The way to do it is “Paint bucket”-tool from top left corner with various colors.

But enough talk. Let’s see some code:

And of course, there is some QML tests for the curious.
A major todo item is saving the high score and getting that to work. Patches welcome. Or pointer to what QML components that can help me with that.

Managing cooking recipes

I like to cook. And sometimes store my recipes. Over the years I have tried KRecipes, kept my recipes in BasKet notes, in KJots notes, in more or less random word processor documents.

I liked the free form entering recipes in various notes applications and word processor documents, but I lacked some kind of indexing them. What I wanted was free-ish text for writing recipes, and some thing that could help me find them by tags I give them. By Title. By how I organize them. And maybe by Ingredient if I don’t know how to get rid of the soon-to-be-bad in my refridgerator.

Given I’m a software developer, maybe I should try scratch my own itch. And I did in the last month and a half during some evenings. This is also where my latest Qt and modern C++ blog posts comes from

The central bit is basically a markdown viewer, and the file format is some semi structured markdown in one file per recipe. Structured in the file system however you like it.

There is a recipes index which simply is a file system view with pretty titles on top.

There is a way to insert tags into recipes.

I can find them by title.

And I can find recipes by ingredients.

Given it is plain text, it can easily be synced using Git or NextCloud or whatever solution you want for that.

You can give it a spin if you want. It lives here There is a blueprint for a windows installer here:

There is a markdown file describing the specifics of the file format. It is not declared 100% stable yet, but I need good reasons to break stuff.

My recipe collection is in my native language Danish, so I’m not sure sharing it for demo purposes makes too much sense.

Where KDEInstallDirs points to

The other day, some user of Extra CMake Modules (A collection of utilities and find modules created by KDE), asked if there was an easy way to query cmake for wherever the KDEInstallDirs points to (KDEInstallDirs is a set of default paths that mostly is good for your system, iirc based upon GNUInstallDirs but with some extensions for various Qt, KDE and XDG common paths, as well as some cross platform additions). I couldn’t find an easy way of doing it without writing a couple of lines of CMake code.

Getting the KDE_INSTALL_(full_)APPDIR with default options is:

and various other options can be set as well.

This is kind of simple, but let’s just share it with the world:

I don’t think it is complex enough to claim any sorts of copyrights, but if you insist, you can use it under one of the following licenses: CC0, Public Domain (if that’s in your juristiction), MIT/X11, WTFPL (any version), 3-clause BSD, GPL (any version), LGPL (any version) and .. erm. whatever.

I was trying to get it to work as a cmake -P script, but some of the find_package calls requires working CMakeCache. Comments welcome.

Modern C++ and Qt – part 2.

I recently did a short tongue-in-cheek blog post about Qt and modern C++. In the comments, people discovered that several compilers effectively can optimize std::make_unique<>().release() to a simple new statement, which was kind of a surprise to me.

I have recently written a new program from scratch (more about that later), and I tried to force myself to use standard library smartpointers much more than what I normally have been doing.

I ended up trying to apply a set of rules for memory handling to my code base to try to see where it could end.

  • No naked delete‘s
  • No new statements, unless it was handed directly to a Qt function taking ownership of the pointer. (To avoid sillyness like the previous one)
  • Raw pointers in the code are observer pointers. We can do this in new code, but in older code it is hard to argue that.

It resulted in code like

By it self, it is quite ok to work with, and we get all ownership transfers documented. So maybe we should start code this way.

But there is also a hole in the ownership pass around, but given Qt methods doesn’t throw, it shouldn’t be much of a problem.

More about my new fancy / boring application at a later point.

I still haven’t fully embraced the c++17 thingies. My mental baseline is kind of the compiler in Debian Stable.

Modern C++ and Qt

– ’cause raw new’s are bad.