Dev Blog
Typical title for developers blog. Contains boring things.

Collecting Interface Implementations with Signals

When using our favorite IDE, we usually have option to find all implementations of interface. This gives us overview of available classes that can do certain operations or have certain purpose. When developing modular application the new types might appear when we install additional dependencies. As well some implementations - through less common - could possibly disappear on dependency upgrade. We have developers tools to to keep our applications up to date to our or external vendor dependencies. But, hey we are developers who do not like to track manually all changes, as it's error prone and tedious. For instance if we have some notification interface and bunch of notifiers. At some point we need to collect those notifiers and notify with them about our application action. The other example might product interface indicating that class represents some kind of product in our system. Then when creating new product, we've had to choose which one from the list of all implementations of product interface. To avoid hardcoding such list of available implementations we could use configuration file to set up all available options. But that's in fact hardcoding configuration, as it would likely be committed with code.

Introducing Mangan Aspects

The Mangan project has now a new features called Aspects. This feature allows adding extra information on what is going on with our data model. Most importantly, this allows several different aspects to be present at the same time. This allows application logic to react differently in many cases, depending on so called point of view. In other words, the data model can have now many different states or scenarios (called aspects) at once. Application component which receives data model, can check if particular state exists and react accordingly or skip some operations. This might be also used to perform more heavy operations only when really necessary.

Abstracting Out Things

When we build our application or library, we often use external packages which provide many kinds of features and are often battle tested and popular. Especially there are a lot of open source libraries made by independent developers. For instance, we can use libraries to perform single sign on authentication, to manage browser history states or to access remote API of other web application. In fact our project might consist of even hundreds of such dependencies.

Ubuntu 18.04

Today is release date of new long term supported Ubuntu. There will be much improvements for people switching from 16.04 version. The new 18.04 is quite similar to shortly supported 17.10. The user interface is much more clean and modern than previous one, thus installing custom theme might not be necessary for those visual purists like me:). Of course when talking about any Linux release, the login screen must be mentioned! The one in new Ubuntu requires us to slide it to see actual credentials inputs. Might be good for some mobile devices, but on laptops with mouse or touchpad it's a bit overkill.

Upgrading from 17.10 went smooth almost till the end on beta version, then some error appeared. However upgrade was successful. The system runs fast even on older laptop, especially after disabling animations. There servers will need to be upgraded to new release too, but that's the whole different story.

To upgrade to stable version use this console command:
sudo do-release-upgrade

And follow instructions. Lot of packages will be downloaded, upgraded and some will be removed. It is recommended to review those. Also all custom apt sources lists will be disabled. Use Y PPA Manager for easier migrations of sources lists.

To install Y PPA Manager add it's repository first, than update and install:

sudo add-apt-repository ppa:webupd8team/y-ppa-manager
sudo apt update
sudo apt install y-ppa-manager

Then choose Advanced and use Re-enable working PPAs after Ubuntu upgrade. This will enable whatever works now. You can try to run it later again when other sources lists get's updated.