Arnaud Rebillout Learning GObject
Mon 28 November 2016I worked on a C/GObject project for a while now, and had to learn GObject from scratch. Learning GObject is definitely not the easiest thing to do, it's much more than just learning to use a new library. Hence this "bookmark article", that list the best links I found so far. Hope this helps other learners like me.
How Do I Learn GObject?
First, you need to bookmark the official documentation. It's the best place to start, but also a good place to go back afterward. Things that don't make sense at the first reading will become clear as you go further.
Second, there's one essential article that nicely sums up the GObject construction process, and raise some important points around it. This article you will have to read again and again.
At last, you need code example, although the code you find is not always up-to-date with latest/best way to do things. Anyway. The main GObject-based libraries are probably the best places to go to learn GObject. Grab the source code, sharpen your grep, and there you go.
Good Practices
Follow The Conventions
The first place to learn about good practices is the GObject conventions page.
It's more than good practice actually. GObject expects you to follow a few
conventions, so that code generation tools (glib-mkenum) and other stuff can
actually work. Don't try to avoid that.
Use G_DECLARE_* And G_DEFINE_*
Do not clutter the header file with too much boilerplate, as it's often seen in some old GObject-based code.
Do The Minimum In _init()
There should be almost nothing in the init() function. Most of the time,
it just boils down to setting up the private pointer, if any.
For all the rest, it's better to implement it in the constructed() method.
Always Use A Private Pointer
Using a private structure is particularly useful for derivable objects, since for these objects, the structure MUST BE defined in the header (public) to allow inheritance. But when the object is not derivable, and therefore the structure is defined in the code (private), what the point of having a private struct? Answer: consistency, and less hassle when the objects change from final to derivable, or the other way around.
Best Way To Set Properties
The correct way to set an object pointer. It's not as trivial as it seems.
Quick FAQ
How To Change A Construct-Only Property Via Inheritance
This questions is asked on StackOverflow:
http://stackoverflow.com/q/16557905/776208
Unfortunately, the answer given by Emmanuele Bassi is wrong, and it seems that the only other solution is to hack around, as did the guy who asked the question.
There's another solution though: don't use construct-only properties if they are to be modified by the inherited objects. Make them constuct.
How To Implement A Singleton
This is discussed here and there on the Net.
How To Have Protected Fields
GObject doesn't provide any solution to have protected fields. I managed to do without up to now, but just in case, here's a workaround. Basically, it's just about defining the private structure in the header (therefore making it public), and naming it 'protected' instead of 'private'.