The C# Interface ISerializationListener is undocumented

[Lennart-Bours]

Your Godot version:

4.3

Issue description:

If you are using C# in your Godot project, you can implement ISerializationListener to execute code in OnBeforeSerialize and OnAfterDeserialize. These functions are called when building the C# solution, and perhaps also in other circumstances?

This feature can be helpful if you have to acount for serialization in your [Tool] scripts, but is completely undocumented. I only found out about its existence via this informative issue: godotengine/godot-proposals#9001

Frankly, it would be helpful if all the information in that issue was added to the documentation. The Godot API for C# section seems like a logical place.

I can attempt to write the documentation, but I'm not particularly knowledgable about the behaviour of ISerializationListener, and even less on the entire process of rebuilding the C# solution.

URL to the documentation page (if already existing):
N/A

[raulsntos]

The ISerializationListener interface is intentionally undocumented because we don't want to encourage its usage. It likely should have been internal from the beginning.

In the engine code we use it to maintain state across assembly reloads. The process of reloading the .NET assemblies is indeed quite complicated and ideally not something users should need to worry about.

We'll likely change the reloading process in the future and we don't want to limit ourselves to the current ISerializationListener design, we may want to change it.

[Lennart-Bours]

That there are good reasons to discourage the use of the interface, I can understand. Still, it is strange to me to choose to keep it undocumented. This creates a situation where the intent of the interface is unclear, and doesn't warn a potential user that discovers its existence against using it. Also because it pops up in a number of Issues, see for example also this one: godotengine/godot#90837. And after finding it in these issues, I used it to create a work-around for this issue I encountered: godotengine/godot#102455.

Would it not be clearer to add it to the documentation with the strong warning against relying on it?

[4everalone]

Folks, you should work backwards from developers who support your engine and who will want to try it out. I found this interface only after several months of Godot usage and all this while i had to keep restarting Godot. Every developer that tries Godot engine will face with this issue. Think how many people will be turned away from Godot and how many users Godot will lose if you do not provide solution for this problem. Only handful of people will be stubborn enough to read godotengine/godot#78513, less will understand what is the solution after reading it fully. And even less people know how assemblies work and how to debug them.
You know Godot engine the best and when you say that ISerializationListener shouldn't have been exposed I believe you. However, this seems to be the only workable solution for your customer base. You can wait longer before you'll rework assemblies unloading, but how long has it been already?