Using constructor DSL to bind multiple classes via lambdas to the same interface does not work

[sschuberth]

Describe the bug

The code

module {
    singleOf(::CsvExporter) { bind<Exporter>() }
    singleOf(::ExcelExporter) { bind<Exporter>() }
}

throws org.koin.core.error.DefinitionOverrideException: Already existing definition for [Singleton:'dev.schuberth.stan.exporters.ExcelExporter',binds:dev.schuberth.stan.exporters.Exporter] at dev.schuberth.stan.exporters.Exporter::_root_.

Note that using the alternative operator-syntax

module {
    singleOf(::CsvExporter) bind Exporter::class
    singleOf(::ExcelExporter) bind Exporter::class
}

works.

To Reproduce

Just use above code snippets.

Expected behavior

{ bind<Exporter>() } syntax should work just like bind Exporter::class syntax.

Koin project used and used version (please complete the following information):

koin-core version 3.2.2

Additional moduleDefinition

n/a

[1gravity]

IMO

module {
    singleOf(::CsvExporter) bind Exporter::class
    singleOf(::ExcelExporter) bind Exporter::class
}

should also throw a DefinitionOverrideException because you're binding two implementations to the same interface and Koin doesn't know which one to inject. It seems to pick the second one but

1. that's not a documented behavior and
2. it makes the first bind obsolete so why add it in the first place (ok I know what you're trying to do but outside of your use case, having these two binds in one module doesn't make sense)?

[sschuberth]

ok I know what you're trying to do but outside of your use case, having these two binds in one module doesn't make sense

Yes, as you know from my SO question I'm looking at Koin from a Service Locator / plugin registry perspective. And there, it makes sense to be able to bind multiple implementations to the same interface, so all plugin instances could be retrieved via app.koin.getAll<Exporter>(). If that shouldn't be allowed, what's the purpose of the getAll() API call after all?

[1gravity]

ok I know what you're trying to do but outside of your use case, having these two binds in one module doesn't make sense

Yes, as you know from my SO question I'm looking at Koin from a Service Locator / plugin registry perspective. And there, it makes sense to be able to bind multiple implementations to the same interface, so all plugin instances could be retrieved via app.koin.getAll<Exporter>(). If that shouldn't be allowed, what's the purpose of the getAll() API call after all?

Yes you're right, I didn't understand that Koin indeed allows to inject multiple implementations that can be retrieved into a list .

[arnaudgiuliani]

I fixed it back, to allow bind() for 2 same type