How do I add a module? Looking for a thorough, systematic and in-depth explanation. Long post

[kamrann]

@Nastymonk

It seems that there are two ways to expose functionalities across DLL boundaries. The first one is Module API, which is dllimport/dllexport under the hood. However, in the last several sentences in Unreal Module API, it states that “The API macros are mostly used on older code to allow newer modules to access it from their DLL. In newer bits of code, the API macros are used far less, instead setting up nice interface layers to expose functionality across DLL boundaries.”

How does this setting up nice interface layers work? Can you provide me with an example? Thank you very much!

That’s a bit misleading really. It’s true they’ve begun to use the latter approach more, but the bulk of the engine is still reliant on exporting symbols. The interface approach is definitely better where feasible (since you can then use a dynamic dependency making your modules less tightly coupled), but it’s far more restrictive. It should be used whenever you have some self contained piece of functionality, service or whatever, that naturally can be exposed through one or more interfaces.

In the engine, you can look at the asset registry and asset tools modules as examples. One of my plugins does it here, though it might be a bit convoluted since it was tacked on afterwards.

Also be aware that UE4’s reflection system doesn’t always play nice with this approach. If you have public reflected types, you may find cases where you need a full dependency, when with regular types a dynamic dependency would have worked.