Debconf 2015 – 5

Watching people figuring out how to use a Danish cheese slicer is kind interesting. But by using enough force most people succeeding in getting a lump of cheese.

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Debconf 2015 – 4

“I refuse to be bound by software I cannot negotiate with” — enrico

Posted in debian, english

Debconf 2015 – 3

It is still an open question what the Debian Project Leader wears under their kilt.

Posted in debian, english

Debconf 2015 – 2

It is amazing at debconf when your Application Manager is rocking the dance floor!

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Debconf 2015 – 1

When greeted by Clint with one single word: “kamelåså“, one has arrived to Debconf.

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Getting a Q_INVOKABLE C++ function reevaluated by QML engine

Unfortunately, with all the normal magic of QML property bindings, getting a property updated in a setup that involves return values from functions isn’t really doable, like this:

I’m told there is a low priority feature request for a way of signalling that a function now returns a different value and all properties using it should be reevaluated.

I have so far discovered two different workarounds for that that I will be presenting here.

Using an extra property

Appending an extra property to trigger the reevaluation of the function is one way of doing it.

with the following on the C++ side:

This is a bit more code to write and to remember to use, but it does get the job done.

Intermediate layer
Another way is to inject an intermediate layer, an extra object, that has the function. It can even be simplified by having a pointer to itself.

with the following on the C++ side:

It seems a bit simpler for the reader on the QML side, but also gets the job done.

I am not sure which way is the best one, but the intermediate layer has a nicer feeling to it when more complicated types are involved.

Posted in english, kde, qt

QImage and QPixmap in a Qt Quick item

For reasons I don’t know, apparantly a Qt Quick Item that can show a QImage or a QPixmap is kind of missing. The current Image QML item only works with data that can be represented by a URL.

So I wrote one that kind of works. Comments most welcome.

It is found on git.kde.org: http://quickgit.kde.org/?p=scratch/sune/imageitem.git

Oh, and the KDE End of Year fundraiser is still running. https://www.kde.org/fundraisers/yearend2014/. Go support it if you haven’t already.

Posted in english, kde, qt

Is linux about choice?

Occasionally, various quotes from people having an opinion if linux is about choice or not. Even pages like http://www.islinuxaboutchoice.com/ has shown up.

My short answer is “YES”. Linux is about choice. And you get all your choices directly from your f/loss definition of choice (FSF’s 4 freedoms / OSI’s opensource definition / Debian Free Software Guidelines)

It doesn’t mean that you get all the gui configuration bits that you want. It doesn’t mean that you without any problems can switch out any component. But it does mean that you can get it exactly your way. But it might require you to edit some source code and compile some stuff.

Posted in debian, english, kde

KDE makes Qt

Recently I was trying some statistics on the qtbase-module (where QtCore, QtGui, QtWidgets and so on lives) and was wondering who made them.
Not based on their current paid affilation, like Thiago’s graphs, but if each commit was made by a person coming from KDE.

So, I got hold of Thiago’s scripts, a lovely mix of perl and zsh, and a QtBase git repository. First steps was to try to classify people as person coming from KDE or not. Of course, I’m a KDE person. Thiago is a KDE person. David Faure is a KDE person. Olivier Goffart is a KDE person. Lars Knoll is a KDE person.

By the help of the KDE accounts file, and some of the long time KDE contributors, I got after a half day of work a good list of it. Then next steps was trying to put it into Thiago’s perlscripts

All of it kind of succeeded:

qtbase-KDE.graph

So, KDE people makes up for 40-60% of the weekly commits to QtBase. This is again shows that KDE is important to Qt, just as the reverse is. So, let’s keep KDE healthy.

KDE is running a end-of-year fundraiser over here https://www.kde.org/fundraisers/yearend2014/. Go ahead and donate, and help KDE stay healthy. For your own sake. And for Qt’s.

Posted in english, kde, qt

Fun and joy with .bat files

Occasionally, one gets in touch with kind of ‘foreign’ technologies and needs to get stuff working anyways.

Recently, I had to do some various hacking with and around .bat files. Bat files are a kind of script files for Microsoft Windows.

Calling external commands

Imagine need to call some other command, let’s say git diff. So from a cmd thing, you would write

similar to writing shell scripts on unixes. But there is a catch. If the thing you want to call is another bat-script, just calling it ensures it ‘replaces’ the current script and never returns. So you need

if the command you want to run is a bat file and you want to return to your script.

Calling an external helper next to your script
If you for some reason needs to call some external helper placed next to your script, there is a helpful thing to do that as well. Imagine your helper is called helper.bat

is the very self-explanatory way of doing that.

Stopping execution of your script

If you somehow encounter some condition in your script that requires you to stop your script, there is a command ‘exit’ handy. It even takes a argument for what error code there is.

stops your script with return code 2. But it also have the nice added feature that if you do it in a script you run by hand in a terminal, it also exits the terminal.

Luckily there is also a fix for that:

and it doesn’t exit your interactive terminal, and it sets the %ERRORLEVEL% variable to the exit code.

Fortunately, the fun doesn’t stop here.

If the script is run non-interactively, exit /b doesn’t set the exit code for for example perl’s system() call. You need to use exit without /b for that. So now you need two scripts. one for “interactive” use that calls exit /b and a similar one using exit for use by other apps/scripts.

Or, we can combine some of our knowledge and add a extra layer of indirection.

  • write your script for interactive use (with exit /b) and let’s call it script.bat
  • create a simple wrapper script
  • call the wrapper for non-interactive use

and then success.

Oh. and on a unrelated note. Windows can’t schedule tasks for users that aren’t logged in and don’t have a password set. The response “Access Denied” is the only clue given.

Posted in english, kde