You may be aware that Linux Mint has forked several GNOME applications, either directly from GNOME (Totem -> Xplayer, Evince -> Xreader, Eye of GNOME -> Xviewer), or indirectly via MATE (gedit -> pluma -> XEd).
GNOME is like the Debian of the Linux desktops. But is it a good thing? In the current state of the code, I don’t think so and I’ll explain why, with a solution: creating more shared libraries.
At the end of the day, it’s just a matter of design and usability concerns. We can safely say that the main reason behind the forks is that the Linux Mint developers don’t like the new design of GNOME applications with a GtkHeaderBar.
And there are perfectly valid reasons to not like headerbars. For gedit for example, see the list of usability regressions at this wiki page.
Currently the trend is GtkHeaderBar, but what will it be in 5 years, 10 years? Let’s face it, GNOME is here just following the new trend that came with smartphones and tablets.
So, a GNOME application developer needs to know that:
- A GUI is an ever-changing thing, exactly like the clothes that you bought last year are already obsolete, right?
- When the GUI changes too much, other developers don’t like it and fork the project. For valid reasons or not, this doesn’t matter.
The four X-Apps forks account for roughly 200k lines of code. In the short-term it works, Linux Mint has apps with a traditional UI. But hey, porting the code to GTK+ 4 will be another beast, because the four X-Apps still use the deprecated GtkUIManager and GtkAction APIs, among other things.
But when we look at the codebase, there are a lot of code that could be shared between a GNOME app and its fork(s). So there is a solution: creating more shared libraries. The shared libraries would contain the backend code, of course, but also some basic blocks for the UI. The application would just need to glue things up together, assembling objects, binding GObject properties to GSettings, create the main GtkWindow and a few other things.
The difference would be that instead of forking 200k lines of code, it would be forking maybe 20k lines, which is more manageable to maintain in the long term.
In the case of gedit, making its code more re-usable is exactly what I do since several years, but for another reason: being able to create easily specialized text editors or small IDEs.
Beside avoiding code duplication, creating a shared library has the nice side effect that it is much better documented (usually), and with an API browser like Devhelp, it’s a breeze to discover and understand a new codebase, it permits to have a nice overview of the classes. It’s of course possible to have such documentation for application code, but in practice few developers do that, although it would be a big step towards lowering the barrier to entry for newcomers.
When untangling some code from an application and putting it in a shared library, it is also easier to make the code unit testable (and unit tested!), or at least write a mini interactive test in case of frontend code. Making the code more stable, getting closer to bug-free code and thus more successful software.
Developing a shared library doesn’t necessarily mean to provide backward compatibility during 10 years. Nothing prevents you from bumping the major version of the library every 6 months if needed, making the new version parallel-installable with the previous major versions. So that applications are not forced to update the code when there is an API break.
But creating a library is more difficult, API design is hard. But in my opinion it is worth it. GNOME is not only a desktop environment with an application suite, it is also a development platform.