Are the contents of a fragment visible outside the host plugin?

Question

I have never worked with plug-in fragments before. I thought that by creating a new class within a fragment and exporting the package that contains it in the fragment's manifest, I'd be able to access that class from another plug-in that already has a dependency on the host plug-in. However, I cannot seem to make this work. Are the contents of a fragment ever visible to any plug-in besides the host plug-in? If so, is there something special I have to do to allow this?

Answer 1

The problem is not, that the contents of the fragment aren't visible to another plugin: They are - just try loading e.g. a properties file from the classpath, it still works if that properties file is provided by the fragment.

But what you don't have, is compile-time information about the fragment's contents. That's the principle of a fragment: You can't have a dependency on it. And you don't know, if somebody has fragments installed or not.

It's also not only a problem that just "any plug-in besides the host plug-in" has. It's a problem, that even the host-plugin itself has. It doesn't know about the fragment's existence at compile-time.

You also can't reliably use a fragment to override parts of the host plug-in's classes: FAQ Can fragments be used to patch a plug-in? , if that's what you want to do. The page also describes, how it can be done.

Hope this helps.