I have a set of Scala projects and for all of those projects, I would like to introduce some scala source code formatting for which purpose, I'm using the scamafmt sbt pliugin. I have compiled the config file and this config file is in a separate project repo. I would now like to reuse this in all of the other Scala projects. I see two possibilities:
Use the repo where the conf file is located as a git submodule in all the other 10 projects where I want to run the scala formatter
Do not do anything, just add a README documentation that every user who is working on the codebase should download the scalafmt conf file to the project (I will pre add a .gitignore to all projects to ignore the local conf file)
Is there any other approach? I definitely do not want the conf file to diverge if I leave it as is in all the projects.
As per the documentation, one option is to build (and publish in your org) a SBT plugin with your configuration:
https://scalameta.org/scalafmt/docs/installation.html#share-configuration-between-builds
To share configuration across different sbt builds, create a custom sbt plugin that generates .scalafmt-common.conf on build reload, then include the generated file from .scalafmt.conf
// project/MyScalafmtPlugin.scala
import sbt._
object MyScalafmtPlugin extends AutoPlugin {
override def trigger = allRequirements
override def requires = plugins.JvmPlugin
override def buildSettings: Seq[Def.Setting[_]] = {
SettingKey[Unit]("scalafmtGenerateConfig") :=
IO.write(
// writes to file once when build is loaded
file(".scalafmt-common.conf"),
"maxColumn = 100".stripMargin.getBytes("UTF-8")
)
}
}
// .scalafmt.conf
include ".scalafmt-common.conf"
I'm just starting with Scala and have run into a problem that has me stumped, but I'm guessing that I'm missing something easy.
I was following instructions to use the Clapper ClassFinder:
http://thoughts.inphina.com/2011/09/15/building-a-plugin-based-architecture-in-scala/
val classpath = List("./plugins").map(new File(_))
val finder = ClassFinder(classpath)
val classes = finder.getClasses
val classMap = ClassFinder.classInfoMap(classes)
After executing the first line, I see that classpath is set simply to
List(.\plugins)
I'm running this on windows, so the swapping of the slash seems to be OK.
But I expected to see a list of File objects, although I am not sure about this Scala syntax, and perhaps I'm missing something in the Scala IDE. The value for classes shows an "empty iterator".
It seems not to be finding any files in the path that I specified. I tried using an absolute path, but I had the same results. I have a single jar file in the plugins directory that I'm hoping it will find. The plugins directory is at the root of the Play2 project I'm using.
Edit ---
I did find that when I explicitly list the path to one jar that it is able to find it:
val classpath = List("./plugins/myPlugin.jar").map(new File(_))
But I want to find all jar files in the directory.
The following didn't work:
val classpath = List("./plugins/*").map(new File(_))
Nor did this:
val classpath = List("./plugins/*.jar").map(new File(_))
Judging by this issue on the ClassFinder repo on Github it may be a bug.
I think you need to create an explicit list of jar files or to list the ones contained in your folder like:
val classpath =(new File("./plugins")).listFiles.filter(_.getName.endsWith(".jar"))
EDIT: from a cursory glance at ClassFinder's source on GitHub I think it's not a bug. ClassFinder searches for .class files either in jars or in zip files or directly in folders but it looks like it does not mix these things recursively (i.e. if you give it a folder it will look for classes directly in the folder but it won't look for classes in jars in the folder)
if you objective is to list all jar files, you can use following code:
val classpath = List("./plugins").map(path => Option(new File(path).listFiles).getOrElse(Array.empty[java.io.File]) filter(file => file.isFile && file.getName.endsWith(".jar"))).flatten
I recently decided to use SBT to build an existing project.
In this project I have some .glsl files within the scala packages which I need to copy during the compilation phase.
The project is structured like this :
- myapp.opengl
- Shader.scala
- myapp.opengl.shaders
- vertex_shader.glsl
- fragment_shader.glsl
Is this file structure correct for SBT or do I need to put the .glsl files into an other directory. And do you know a clean way to copy these files into the target folder ?
I would prefer not putting these files into the resources directory since they are (non-compiled) sources files
Thanks
I would not recommend putting those files into src/main/scala as they do not belong there. If you want to keep them separate from your resource files, you can put them in a custom path, e.g. src/main/glsl and add the following lines to your project definition to have them copied into output directory:
val shaderSourcePath = "src"/"main"/"glsl"
// use shaderSourcePath as root path, so directory structure is
// correctly preserved (relative to the source path)
def shaderSources = (shaderSourcePath ##) ** "*.glsl"
override def mainResources = super.mainResources +++ shaderSources
I have installed Eclipse 3.5.2 and today's Scala plugin from /update-current (that's Scala 2.8 final.) I can compile and run Scala projects consisting of a single singleton object that implements main().
But, if a project contains more classes, I receive the "Could not find the main class" error.
I have tried searching for the solution and I discovered:
Eclipse is correctly looking for the Main$ class, not the Main class
* under Debug Configurations, my main class is correctly identified as mypackage.Main
* my plugin is up to date and recommended for my version of Eclipse
* cleaning, restarting etc. doesn't help.
The same project will compile with scalac.
Thanks for any ideas on how to solve this.
EDIT: MatthieuF suggested I should post the code.
This snippet produces an error. It's not the most idiomatic code, but I wrote it that way to test my environment. I tried it as a single file and as separate files. It DOES work with scalac.
import swing._
class HelloFrame extends Frame {
title = "First program"
contents = new Label("Hello, world!")
}
object Hello {
val frame = new HelloFrame
def main(args : Array[String]) : Unit = {
frame.visible = true
}
}
BUT, if I nest the definition of HelloFrame within Hello, it works. This snippet runs perfectly:
import swing._
object Hello {
class HelloFrame extends Frame {
title = "First program"
contents = new Label("Hello, world!")
}
val frame = new HelloFrame
def main(args : Array[String]) : Unit = {
frame.visible = true
}
}
For me, the problem was that there was a build error (see Problems tab) which was preventing compilation; oops! The reason you see the error is that the run macro proceeds despite the failed compilation step, and attempts to run class files it expects to be there; they don't exist because there was a build error preventing compilation, so it says it can't find Main (not compiled).
Problem goes away when build can complete successfully, i.e. errors are fixed.
I guess, theoretically, there may be more complicated reasons your build is not completing successfully that are not listed in Problems.
One possibility is that you are trying to launch using ctrl-F11, but from a different class.
The Scala Eclipse plugin does not obey the defaults for Java launching. In Preferences->Run/Debug->Launching, there are some options Launch Operation->Always Launch the previously selected application, etc. This currently does not work in the Scala eclipse plugin. To launch a specified main, you need to launch it from the editor for the class.
There has been a bug raised for this. http://scala-ide.assembla.com/spaces/scala-ide/tickets/1000023-scala-launch--does-not-follow-jdt-behaviour
EDIT: This is now (mostly) fixed.
For me it was Eclipse specific problem. I noticed that .class file wasn't built at all. So bin directory doesn't have compiled classes.
When I manually compiled *.scala file using *.sbt and copied it to bin directory it was working as expected.
I tried different tips and tricks and it wasn't worked until I reinstalled Scala plugin in Eclipse .
I'd solve similar problem by executig "Project->Clean.." with next automatically building.
I had the same error message with a Java application made by myself.
The problem was that I deleted (though inside Eclipse) a jar that belonged to the Java build path, without deleting it from the Java build path (project's Properties window). When I did it the class could compile and run again.
Make sure that the .class files exist, usually below the bin directory.
In particular, if you have errors in unrelated files in the same project then the compilation may fail, and no .class files will be produced.
There can be the case of projects, containing errors, added to the build path of the application which prevents the completion of successful compilation. Make sure you remove any such project from the build path before running the application.
Removing these projects solved the problem for me.
Do you have a proper build tool setup? Like sbt have you installed it?
You can check its version by $sbt --version
If it is not setup you can download from here http://www.scala-sbt.org/download.html
You might have to restart your eclipse after installation.
Just copy your XXX.scala file code. Remove the package and create a new Scala Class. Paste your XXX.scala code. (If you are using maven, do a maven clean and build.) Run configuration again. This works for me.
I have faced this issue. I have just deleted the package name, created scala class, Written the same code, Set Build to "Build Automatically". Finally, It works perfectly fine.
Check scala-ide.log
For me the issue was that there were errors on:
AppData\Local\Temp\sbt_10d322fb\xsbt\ClassName.scala:16: error: not found: value enteringPhase
enteringPhase(currentRun.flattenPhase.next) { s fullName separator }
If you are using Intellij, mark directory as source root
I want to create an Action to automate GCJ compilation. Since I couldn't make it work with Ant, I decided to try SBT. The docs say how to create an Action and how to run an external process. What I don't yet see is how to reuse the directory tree traversal which exists for java and scala compiler Actions. In this case my input files would be all the .class files under a certain root folder. I would also need to specify a specific classpath for GCJ. Any pointers for this would be appreciated too.
I haven't used GCJ much at all and I'm still pretty new at SBT, but this is how I believe you could write a quick task to do exactly what you are looking for with SBT 0.7.1. You can use a PathFinder to grab all of the class files like so:
val allClasses = (outputPath ##) ** "*.class"
Using that PathFinder and the "compileClasspath" top level method, you can construct a task like this which will run gcj using the current project's classpath and compose all of the .class files into one gcjFile:
val gcj = "/usr/local/bin/gcj"
val gcjFile = "target/my_executable.o"
val allClasses = (outputPath ##) ** "*.class"
lazy val gcjCompile = execTask {
<x>{gcj} --classpath={compileClasspath.get.map(_.absolutePath).mkString(":")} -c {allClasses.get.map(_.absolutePath).mkString("-c ")} -o {gcjFile}</x>
} dependsOn(compile) describedAs("Create a GCJ executable object")