How do I package extension functions in a library jar? - gradle

Question

I have a set of extension functions that I would like to package into a jar and include in a project, but I can't seem to assess the extension functions from the jar. I can access non-extension functions from the same jar.
For example if I create a project in Idea including the following file, and build the jar.
package mypackagename.swtbuilder
import org.eclipse.swt.SWT
import org.eclipse.swt.widgets.*
fun myFun() {
println("here")
}
fun Composite.tree(treeStyle: Int = SWT.NONE, init: Tree.() -> Unit): Tree {
val treeWidget = Tree(this, treeStyle)
treeWidget.init()
return treeWidget
}
Then include the jar as a dependency in another project using something like this in the build.gradle file.
dependencies {
compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
compile "org.eclipse.swt:org.eclipse.swt.gtk.linux.x86_64:4.5.2"
compile files('/home/john/development/swt-builder/build/libs/swt-builder-1.0-SNAPSHOT.jar')
}
I can use myFun in the new project, but all the extension functions are unresolved.
import mypackagename.swtbuilder.myFun // this import works
import mypackagename.swtbuilder.tree // this import is "grayed out"
fun main(args: Array<String>) {
val display = Display()
myFun() // this function call works
val myTree = tree { // tree is un-resolved
}
}
What do I need to do to make the extension functions visible?

Answer 1

Silly mistake, the extension functions are visible, they just need to be called in the context of object they are extensions of. In this case a Shell which is a subclass of Composite. I had all this working fine when the extensions and the main were in the same project. I was trying to make the extensions a separate library and got ahead of myself trying to make sure they were imported properly.
fun main(args: Array<String>) {
val display = Display()
val myShell = shell {
tree { }
}
myShell.open()
while (!myShell.isDisposed) {
if (!display.readAndDispatch()) display.sleep()
}
display.dispose()
}