Dart & semver hygiene

Dart & semver hygiene

What is semver?

The term semver means “semantic versioning” and is used to describe software releases.
It is defined here.

The essence of this rule-set is to couple the kind of (API) change with the version of the software. If you make a breaking change then you have to increase the major version and for non-breaking changes you have to increase the minor version (simplified).
This rule-set is the recommended way to version dart packages and all the mechanisms to resolve versions of dependencies rely on that.

What is the problem?

In general, I think semver works quite well, but sometimes it happens that a breaking change slips through.
This can have dramatic consequences.
If a package releases a new version and only increases the minor version or the patch version while still containing breaking changes then builds of dependent projects will fail without the developer specifying a new version.
This is because it is considered best practice (even a requirement) for packages to not depend on an exact version but on a compatible version range. This is done by assuming that any newer version that doesn’t increase the major version is backwards compatible.
But even if you don’t have a direct dependency on that package you might have a transitive dependency (e.g. if a package you depend on depends on that package) and you get your build broken as a result.

Is there something I can do about it?

At least soon™️.

We were facing such a transitive dependency build breakage and I wondered if there is an easy way to integrate a semver check into a CI pipeline and why package maintainers don’t check that automatically.
After some research I was not able to find a utility that could be used to do such a check, so I decided to create one myself.

Welcome dart_apitool


Software developmentFlutter

Two months into the new job


As written here I took the opportunity to work in the mobile app development area full time at BMW.

Now I’m almost two months in my new job, and therefore it’s time to do some recap.


The onboarding went really smooth. I was able to become productive after roughly one week. Everything was prepared very well. I really like the new colleagues. They are very helpful and kind.


It is like a dream has come true. Finally working in the mobile app development area professionally is what I wanted to do for such a long time. I think I have to thank Corona to finally make this possible 😁.
The environment is very professional and full of competencies. So much to learn and plenty of discussion partners for deep technical conversations.

Of course everything is still new, and I learn new things every day. Challenging but so rewarding at the same time. I really like that.

App development at BMW is definitely different from what I expected. I already prepared myself for facing a huge and complex project, but I never expected it to be that big.
I like the role I have there. It is very challenging and diverse. Exactly what I like & need. It really doesn’t get boring 😁.

Hybrid remote work



A new challenge

A new challenge

Current situation

As written in my profile(this is an archived version as the actual about page got updated) my current programmer’s life is divided in two halves. I’m a C++ embedded UI software architect and developer by day and a (Flutter-)Mobile Software Engineer by night.

I really like my day job as it is challenging to work on architectures and software development topics that target a very huge amount of different projects. The problem scope is fascinating and completely different from a very product focused way of working as it focuses on streamlining multiple UI projects in parallel.


Since roughly 10 years I focus most of my spare time programming on mobile app development. Mainly Android apps.

Recently (~ March 2021) I discovered Flutter and since then fell in love with it. Not only does it present a fascinating alternative for developing embedded UI applications and shows a way to finally get rid of C++ developed UI applications it also is a great way of developing cross-platform applications. Either for Android and iOS or for the different desktop systems.

This is why I started working with Flutter at home as well as experimenting with it for embedded UI scenarios and pitched it at work as a viable alternative to Qt/QML that we use today.

From time to time I also watched out for job opportunities (inside Bosch but outside as well) for mobile app development because I really love developing them, and it would be awesome to do that as a main job as well.
Sadly the opportunities here in the region I live were not interesting for me.

Corona changed it all



Flutter 3

Flutter 3

Yesterday during Google I/O Google announced the release of Flutter 3.0.
You can have a look at the full video or read the blog post about Flutter 3 or the one about Dart 2.17.

There are plenty of new features but what stroke me most were two tiny announcements that were part of the Dart 2.17 release notes because they basically target two blog posts I made 😁.

Dart enums

I had a blog post describing how an enum can be extended by using extensions.
In the context of the Flutter 3 announcement they also announced an evolution of enums in Dart.

It is now possible to have a constructor and members directly in enums without using extensions. The only thing we loose is the reverse map providing the fromValue method.
Here is the example from my previous post but adapted to Dart 2.17:


Software developmentFlutter

Flutter and embedded UIs

Flutter and embedded UIs

Hi there. It has been quite a while since my last post.
In the meantime, a bunch of things happened. Corona is over 🥳😉, Apple released a monitor for the masses (webcam cough) and some crazy guy from the east decided to question the European borders 🥴.
But that shall not be the topic of this blog post. Today’s topic is: Is Flutter a good candidate for embedded UIs?
The answer: Yes!
See you next time …

but wait. Let’s explain a bit.


Software developmentMeta

I got myself some new hardware

I got myself some new hardware

Today I want to share my opinion about 2(3) new pieces of hardware that I got for myself as an early expensive Christmas present.

The new Mac lineup

Initially I hesitated to jump on the M1 Pro/Max train. My 13” Intel MacBook Pro worked, I don’t have any projects that have compile-times where I have to wait minutes for them to complete so no real need to upgrade.

I started configuring a MacBook 14” the day the preorders started. I use the 2nd tier M1 Pro, 512 GB Storage and 32 GB RAM and ended up with ~€2700.
My first reaction: Phew, that is really expensive. I have no real need, let’s wait.

Initial community reactions

Then the internet filled with reviews, articles and other videos that all had one thing in common: What a beast of a machine.
Additionally, the order date for the MacBook 14” started moving towards December (I think currently they are somewhere in January) so I felt a bit under stress 😨
The M1 topic stuck with me as I already plan how Flutter could potentially be used at work and in that scenario having an ARM based docker environment that is performant would be a real advantage.
So I did some research to find out if the M1 already has similar performance (or even better performance) than the Intel I have and as it turned out even those are faster. So I almost ordered an M1 MacBook Air.

Buying it

In the end I convinced myself that it would be much better to have the even more performant hardware platform and the crazy fast SSD storage. I found a store that was able to immediately ship the 14” MacBook Pro, so I ordered it. I ordered the super basic entry model (8 cores, 16 GB RAM, 512 GB SSD) because I still think the upgrade price is just crazy. This machine did cost ~€2200 which is still very expensive (at least in my terms) and as the current machine was sufficient upgrading it would even be more crazy than ordering it has been in the first place 😉



PersonalDev Setup

Why trying to preserve control over your privacy for me means running Android

Why trying to preserve control over your privacy for me means running Android


I switched from Android to iOS roughly a year ago. The main reasons for this were:

Apple released “affordable” hardware for the masses

The lowest end iPhones went into a range that “normal” people also can afford. Of course, they are a bit more expensive than the cheapest Android phones you can find but taken Apples update strategy into account (and combining this with the fact that the phone cycle slows down) this has become a real alternative for anyone.

This fact removes the “if you can afford it you can have privacy” label (at least a bit) from Apple that I really disliked.

Apple really puts their marketing into privacy

You can argue if Apple does this because they really think it is the best for their users or - like some people think - because they had no other choice (no way to beat Google, Microsoft or Amazon in the Cloud and data game) but they put privacy on top of almost every marketing material.

So the assumption is that they will try their very best to make sure to deliver on that end because they would really, really harm themselves by violating that rule.

Phones get more “boring”


Using Flutter to teach the next generation - the project

Using Flutter to teach the next generation - the project

This is a quick follow-up to the last two posts.

As I got asked quite often to show off the project the kids implemented I thought it might be quite interesting for the readers here as well.

So I just built the Flutter app for web. I translated the German strings to English for your reading pleasure 🥸

The only problem I had was that on this statically generated blog the project is not the root of the domain, so I had to remove the href=”/“ tag in the index.html for the app to run from a subfolder.

Without further ado, here you can find the tic-tac-toe app:

Depending on your device and browser the experience might have some problems - but you will get the idea

Software developmentFlutter

Using Flutter to teach the next generation part2

Using Flutter to teach the next generation part2

As promised I now want to share how well the teaching experiment went.

How the day went


I used our kitchen table and moved it closer to the TV to mirror the MacBook’s screen to it.
I used AirPlay for that which turned out to be quite laggy (moving the mouse was very hard) so the next time I would rather run an HDMI cable to the TV
Kitchen table
TV showing the MacBook screen


We gathered 6 kids (2 of my kids and 4 friends) and started off discussing what the TicTacToe game has to look and behave like.
I used the version I already created beforehand to show what our goal will be.

After doing that we started Android Studio and created a new project. I explained briefly what the main parts of a Flutter app are and where we will spend our effort at (Position wise). Of course, I didn’t explain all the details of what’s written there. No information about State(less)Widgets, classes or anything on that end.

We started by simply placing 9 texts and layouted them using Columns and Rows. Before we started to fine tune the cells I mentioned that we might want to extract the Text part to a method so that we don’t have to make every modification 9 times.
The concept of a Function was already clear to my children (they used Swift Playgrounds a bit) so they were eager to explain the concept to the other kids.

So we created a method that creates the cell content, moved the Text there and made the content a parameter.
Afterwards we replaced all Texts with a call to that method.
The cells up to that point simply contain the “cell ID” (1-9) to see how the text will look like.


Software developmentFlutter

Using Flutter to teach the next generation

Using Flutter to teach the next generation

What I already tried

I have 3 kids at the age of 12, 10 and 2.
Without trying to be one of the parents that really insists on the kids having to do what the parents enjoy doing I still want to provide enough opportunities for them to get hooked by software development.
The tries I had to this point didn’t really work out:

Board games

I used board games that encourage “programmer thinking” (Robot Turtles). While it was quite funny to play it never stuck, so now it is waiting in the drawer for the 2y old to pick it up one day.

Educational Hardware pieces

I thought “maybe this is too theoretical and there is no connection to the real world” so I bought some hardware that is meant to be controlled by high level visual programming languages (Makeblock).

This also was fun only for a short period of time and then the kids lost interest.

Next plan: Apps

As the older kids are quite tied to their smartphones and given the battle that we as parents have almost every day regarding the smartphone usage (the kids have a very strict screen time with their smartphones) I thought “maybe it would be a good idea if they would be able to create a useful app for their smartphone”.


Software developmentFlutter