Why is the principle stating that "interfaces should belong to the package that uses values of the interface type, not the package that implements those values" sometimes violated?

• etcd

  61 46,345 9.9 Go

  Distributed reliable key-value store for the most critical data of a distributed system

  

While exploring popular projects such as etcd and especially traefik, I noticed a violation of the principle that states "interfaces should belong to the package that uses values of the interface type, not the package that implements those values." For example, Here we can see that ManagerFactory import Registry interface that placed here and implementations of this interface in the same package, which violates the aforementioned principle. Even if the interface is simply a specification, it should still be defined on the consumer side. Is it considered bad practice to follow what traefik does in this case or I doesn't understand somthing? P.S. I'm newcomer, so sorry if it's silly question.

• traefik

  183 47,814 9.4 Go

  The Cloud Native Application Proxy

  

While exploring popular projects such as etcd and especially traefik, I noticed a violation of the principle that states "interfaces should belong to the package that uses values of the interface type, not the package that implements those values." For example, Here we can see that ManagerFactory import Registry interface that placed here and implementations of this interface in the same package, which violates the aforementioned principle. Even if the interface is simply a specification, it should still be defined on the consumer side. Is it considered bad practice to follow what traefik does in this case or I doesn't understand somthing? P.S. I'm newcomer, so sorry if it's silly question.

• WorkOS

  workos.com sponsored

  The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.

  

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