Add a separate install step after adding all subsystems

[imberny]

• this "install" method can be safely used by subsystems which rely on other subsystems
• fixes Crashes new project on start with "Invalid get index 'Settings'..." #1819 which was caused by a subsystem fetching another subsytem not yet in the tree (introduced by [speed], input & text separation update #1718)

Since the subsystems are loaded by parsing the directory, I assume the order might vary by OS (I'm on Linux and could reproduce #1819).

[imberny]

Changed the method's name to post_install to better reflect its usage.

[Jowan-Spooner]

Interesting. The implementation looks pretty clean. I think the original issue could've been solved by just adding
await get_parent().ready
before the Settings.connect statements in the Text subsystem.

So now I'm torn between the simple and the proper solution...

[coppolaemilio]

@Jowan-Spooner if you think there's a proper solution to this it should be that. The simple solution now might be a headache in the future

[imberny]

I guess it depends how often you expect subsystems to rely on eachother. The original issue (I suspect) is due to different OSes loading the subsystems in different orders, meaning it could work for the developer working on a subsystem, but break for others. The benefit of this post_install step is to make it explicit that this is where you put inter-subsystem code.

But as I am very new to this project it could be that such interdependences ought to be rare and that a simple await would do the trick, as long as people remember to include it.

[Jowan-Spooner]

No, I agree with Emi that a proper solution (such as this PR provides) is likely the better way. Also to answer the question on the review comment, yes all subsystems can be expected to be of tpye DialogicSubsystem so a static declaration would be good.

Thanks for this work!

[imberny]

Ok @Jowan-Spooner, I've added an assert as well as a DialogicSubsystem return type. I think the assert is good here, since we already expect that the script would declare a dialogic member variable and thus shouldn't just be any script.

[Jowan-Spooner]

@imberny Thank you!