Open Question: What is the general solution for handling optional dependencies in project?

[amirebrahimi]

After having a lengthy discussion with Lukasz P here at Unity I figured I'd write some of my notes down to capture ideas that could improve CCU or invalidate its need.

Here are some possible paths to explore:

• Make use of the CompilationPipeline (requires 2017.3 or later).
• Use wrapper classes around optional dependencies that bind methods, properties, fields, etc. using Reflection.
• Have a gist/snippet of code that dependencies could have to register themselves with AutoLOD (and possibly use Cecil to inject interface usage back into the assembly; otherwise automagical detection of method signatures would likely be required).
• Have optional dependency C# code with a separate extension that won't compile automatically under Unity and then use the CSharpCodeProvider or Editor.CompileCSharp (similar to what EditorVR does for a test) to create that assembly/code and either load in dynamically (and have in a temp folder) or move the assembly into the project.
• Similar to the above, name the C# file to have a separate extension and then name back when a dependency is detected; This is not likely a good solution as it would not work if the package was immutable.
• When PackMan releases for dev use, potentially move off dependent code into another package that can depend on the optional dependency. Then, a user could select which packages they wanted to include alongside the main package (hopefully, there would be a good way to show these associated packages in the UI).
• This would require some changes to Unity, but a toggle in metadata for a C# file could exist for whether it gets compiled or not, similar to VS.