Dependency initialization for an app, when dependency imported from a swift package.

[cprince-foreflight]

I'm having problems initializing a @Dependency for an app or target which consumes a Swift package which defines that @Dependency. My specific case is that the liveValue has no reasonable default, and that it needs to be overridden by the consuming package. I've looked at the overriding discussed here, but I want the override scoped for the entire application. I think that overriding doesn't do that.

In the defining Swift package, I'm currently exposing the liveValue as a public static var, but that doesn't really seem good.

Thoughts?

[kamcma]

https://swiftpackageindex.com/pointfreeco/swift-dependencies/main/documentation/dependencies/livepreviewtest#Separating-interface-and-implementation

I think this is the answer. In the module that defines the dependency, you only conform it to TestDependencyKey. (Every endpoint can simply be failing. The @DependencyClient macro would do this for you automatically.) Then, in the consuming module, you extend the dependency to further conform to DependencyKey, where you provide the live value.

Feature modules can depend on only the definition module, but the app entry point module depends on (or perhaps contains) the live implementation, so it will be used by the full app.

[acosmicflamingo]

Sounds like what Isowords does for APIClient:
https://github.com/pointfreeco/isowords/tree/main/Sources/ApiClientLive

https://github.com/pointfreeco/isowords/tree/main/Sources/ApiClient

[cprince-foreflight]

Nodding. Thanks! I was initially confused about the Test in TestDependencyKey. I initially thought that Test meant it should not be used with code intended for production, but only for code intended for tests.