Manual/ScriptCompilationAssemblyDefinitionFiles

[giscus[bot]]

Manual/ScriptCompilationAssemblyDefinitionFiles

https://docs.unity3d.com/Manual/ScriptCompilationAssemblyDefinitionFiles.html

[vertxxyz]

Split each assembly into "Editor" and "Runtime" instead of littering your project with Editor folders. Packages use this layout and are a good example of proper script structure.

When adding asmdefs to assets that have Editor folders strewn around the project, you can add one asmdef and use Assembly Defintion References for the remaining folders.

[vertxxyz]

You can use an Assembly Definition Reference to compile code into another assembly—like that of a package—giving you access to its internal members.
You can also create an Assembly Definition with a name matching any of the InternalsVisibleTo attributes mentioned in the UnityCsReference¹ (eg. Unity.InternalAPIEditorBridge.001) to create an assembly that has direct access to the built-in Editor assembly.

Footnotes

1. Some of these names are in-use and may cause unexpected problems when packages using the same technique and name are in use at the same time. ↩

[vertxxyz]

If you want to search for Assembly Definitions in your project use t:AssemblyDefinitionAsset.