Add post about Vala interfaces

_posts/2016-02-26-vala-interface-madness.md

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+---
+layout:    post
+title:     "Vala interface madness"
+date:      2016-02-26 15:07:62+02:00
+tags:      [vala, development]
+published: true
+author:
+  name: "Gergely Polonkai"
+  email: "gergely@polonkai.eu"
+---
+
+Although I have just started making it in C, I decided to move my
+Matrix GLib SDK to Vala. First to learn a new language, and second
+because it is much easier to write GObject based stuff with it.
+
+For the first step I created a `.vapi` file from my existing sources,
+so the whole SDK prototype was available for me in Vala.
+
+I had a `MatrixEvent` class that implemented the `GInitable`
+interface, and many others were subclassed `MatrixEvent`. For some
+reason I don’t remember, I created the following header for one of the
+event classes:
+
+    public class MatrixPresenceEvent : GLib.Object, GLib.Initable {
+
+This is nice and everything, but as I didn’t create an `init()` method
+for `MatrixPresenceEvent`, it tried to use the one from the parent
+class and somehow got into an infinite loop. The Vala transformer
+(`valac`), however, doesn’t mention this.
+
+Lessons learned: if you implement an interface on a subclass that is
+implemented by the parent don’t forget to add the necessary functions
+to the subclass.

blog/tag/vala.html

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+---
+layout: posts-by-tag
+tag:    vala
+---