Unity script compilation stages

1. All scripts in "Standard Assets", "Pro Standard Assets" or "Plugins" are compiled first.

Scripts in one of these folders can't directly access scripts outside these folders.

It is not possible to reference the class or its variables directly, but it is possible to communicate with them usingGameObject.SendMessage.

2. All scripts in "Standard Assets/Editor", "Pro Standard Assets/Editor" or "Plugins/Editor" are compiled next.

If you want to use the UnityEditor namespace you have to place your scripts in these folders. For example to add menu items or write custom wizards you have to place your scripts in those folders.

These scripts can access scripts from the previous group.

3. All other scripts outside "Editor" are compiled next.

All scripts that are not in the folders above or in "Editor" are compiled next.

All scripts that are compiled in this step have access to all scripts in the first group ("Standard Assets", "Pro Standard Assets" or "Plugins"). This allows you to let different scripting languages interoperate. For example, if you want to create a Javascript that uses a C# script: place the C# script in the "Standard Assets" folder and the Javascript outside of the "Standard Assets" folder. The Javascript can now reference the C# script directly.

Scripts that are placed in the first group, will take longer to compile, since when they are compiled the third group needs to be recompiled too. Thus if you want to reduce compile times, put scripts that seldom change into group 1 and scripts that change a lot into group 3.

4. All scripts in "Editor" are compiled last.

If you want to use the UnityEditor namespace you have to place your scripts in these folders. For example to add menu items or write custom wizards you have to place your scripts in those folders.

These scripts can access all scripts in all previous groups.