Hi,
I am not 100% clear, whether I understand the issue (and my Scala
knowledge is close to NIL).
But if Scala really needs an explicit class path (with Strings not
URLs !), I would say, this is a real problem and virtually prevents
Scala from being used in a truly embedded way.
I tend to think, this a fundamental shortcomming of this whole
stuff ....
Maybe Bertrand has more insight...
Of course, there could be a solution to this problem, but to be honest,
I really do NOT like it and would more like consider it a "short-term
workaround to get this thing running" solution and would oppose to any
release of such a thing.
Having said this, here is the solution: Copy the required library to
some filesystem location at runtime and refer to it with the filesystem
path:
BundleContext context = BundleContext of Scala
ScriptEngineFactory bundle
URL resource = bundle.getEntry("name of scala library");
File file =
context.getDataFile("someFolder/scala.lib.name.jar");
// copy resource to file
// add file.getAbsolutePath() to class path
This could could be run at bundle start time. While at bundle stop time,
I suggest to cleanup the filesystem again and remove the library file.
Alternatively you could copy the interpreter file to the file system on
request instead at bundle start time.
But, to repeat myself: The correct solution would be to get Scala to
operate on a ClassLoader and NOT on some class path based on
String-ified URLs
Regards
Felix
Am Montag, den 16.06.2008, 00:40 +0530 schrieb janandith jayawardena:
> Hi,
>
> The report is a bit different this week because my intention was to load the
> scala Interpreter in sling.
>
> I tried to fix the scala interpreter loading problem this week. This is the
> most important thing in sling-scala.
>
> In doing so I found that the Scala Interpreter is a special case of the
> compiler.[1]
> That means a wrapper to the compiler.
> The compiler has to be notified the classpath location to the
> scala-library-2.7.1.jar or other scala-library jar version.
>
> This should be done by passing it using the scala.tools.nsc.Settings object.
> If the classpath is not specified Interpreter will look in the paths it
> guesses as in [2].
>
>
> I tried the following and different variations of them but failed,
>
> 1. Inside the engine I tried the solution suggested by Felix using
> ClassLoader.currentTheread().
>
> 2. loading "scala.tools.nsc.Interpreter" using
> ClassLoader.loadClass("scala.tools.nsc.Interpreter") which returns null.
>
> 3. Reading the URL of the parent class loaders which doesn't go beyond
> "felix://extensions/" I passed this to the Settings.
>
> 4. Using the <Import-package> and <Private-Package> directives in maven.
> These help compiling but doesn't include the scala-library to the current
> class path.
>
> 5. The "maven-scala-plugin" is only able to compile and run scala code using
> the "compile" , "testcompile". There is no "install" goal. This requires
> .scala files. Even though java code can be run in scala I think scala byte
> code cannot be run in the jvm. Although I tried to change the extension
> there were syntax errors because the plugin expects scala syntax for
> methods.
>
> 6. Tried to write a dummy class in scala which creates the interpreter and
> passes it the Setting without absolute path and pass it the script string
> within eval method.
>
> As the bundle ID reads I have tried these a 184 times.
>
>
> My suggested solution,
>
> 1. While compiling in maven copy the
> "m2/repository/org/scala-lang/scala-library/2.7.1/scala-library-2.7.1.jar"
> in to a directory in target/lib and create a plain file with the version.
> Then possible to give the classpath as "/lib/scala-library"+ version +
> "jar".
>
> I don't know whether it's possible in maven or how it's done if possible.
>
>
> 2. Create an osgi bundle using the existing maven dependancy "scala-library"
> in repository to include it in "apache felix". This might help in solving
> the problem but I don't know the correct way to do it. According to what I
> found in google it's possible to create osgi bundles in scala code and
> compile using the "maven-scala-plugin" but what I want is to wrap the
> scla-library as a bundle to load in sling while building using maven..
>
> 3. Setting an environment variable to the maven repository and get the
> classpath using
> "org/scala-lang/scala-library/2.7.1/scala-library-2.7.1.jar".
>
>
>
> I'm currently confused with this problem. I can write tests for the current
> code but even though all other code is completed using
>
> "Settings.classpath().value_$eq("/home/janandith/.m2/repository/org/scala-lang/scala-library/2.7.1/scala-library-2.7.1.jar");"
> temporarily it would leave with the same problem of avoiding path setting in
> the completed project.
>
> What are your suggesstions ?. How can I move forward in solving this issue.
>
>
> [1]
> https://lampsvn.epfl.ch/trac/scala/browser/scala/trunk/src/compiler/scala/tools/nsc/Interpreter.scala
> [2]
> https://lampsvn.epfl.ch/trac/scala/browser/scala/trunk/src/compiler/scala/tools/nsc/Settings.scala
