pedrolamarao / gradle-module-path-decision

Example of a problem caused by Gradle's decision on not using the module path

gradle-module-path-decision

This simple project should respond to ./gradlew run with Hello World!.

Instead, it raises NoSuchElementException.

The cause is Gradle’s decision to put api and impl in the class path instead of the module path. Gradle seems to make this decision based on the fact that app is not a module.

This decision breaks the service loader mechanism. impl declares it’s provided services in its module definition. It is meant to be put in the module path, not the class path.

One may be tempted to avoid this problem by redeclaring impl 's services in META-INF/services. This way, when impl be put in the class path, the service loader is satisfied.

However, api module designers intended for the spi package to have restricted access to impl only. Allowing api and impl in the class path makes this restriction meaningless. To enforce this restriction, api and impl must require the module path.

Currently, one cannot apply this kind of architecture with non-modular Gradle applications.