FAQ
Please use the mailing list for questions, comments, and discussions.
- Please state the problem or question clearly and provide enough context. Code examples and build transcripts are often useful when appropriately edited.
- Providing small, reproducible examples are a good way to get help quickly.
- Include relevant information such as the version of sbt and Scala being used.
Please use the issue tracker to report confirmed bugs. Do not use it to ask questions. If you are uncertain whether something is a bug, please ask on the mailing list first.
- Fix mistakes that you notice on the wiki.
- Make bug reports that are clear and reproducible.
- Answer questions on the mailing list.
- Fix issues that affect you. Fork, fix, and submit a pull request.
- Implement features that are important to you. There is an Opportunities page for some ideas, but the most useful contributions are usually ones you want yourself.
For more details on developing sbt, see Developing.pdf
See the migration page first and then the following questions.
By default, sbt 0.11 loads managed libraries from your ivy cache without copying them to a lib_managed directory. This fixes some bugs with the previous solution and keeps your project directory small. If you want to insulate your builds from the ivy cache being cleared, set retrieveManaged := true and the dependencies will be copied to lib_managed as a build-local cache (while avoiding the issues of lib_managed in 0.7.x).
This does mean that existing solutions for sharing libraries with your favoured IDE may not work. There are 0.11.x plugins for IDEs being developed:
- IntelliJ IDEA: https://github.com/mpeltonen/sbt-idea
- Netbeans: https://github.com/remeniuk/sbt-netbeans-plugin
- Eclipse: https://github.com/typesafehub/sbteclipse
For a list of commands, run help. For details on a specific
command, run help <command>. To view a list of tasks defined on
the current project, run tasks. Alternatively, see the
Running page in the Getting Started Guide for descriptions of common commands and tasks.
If in doubt start by just trying the old command as it may just work. The built in TAB completion will also assist you, so you can just press TAB at the beginning of a line and see what you get.
The following commands work pretty much as in 0.7 out of the box:
reload
update
compile
test
test-only
publish-local
exit
sbt 0.10 fixes a flaw in how dependencies get resolved in multi-module projects. This change ensures that only one version of a library appears on a classpath.
Use last update to view the debugging output for the last update run. Use show update to view a summary of files comprising managed classpaths.
Be aware that compilation and tests run in parallel by default in sbt 0.11. If your test code isn't thread-safe then you may want to change this behaviour by adding one of the following to your build.sbt:
// Execute tests in the current project serially.
// Tests from other projects may still run concurrently.
parallelExecution in Test := false
// Execute everything serially (including compilation and tests)
parallelExecution := falsewarn, info, debug and error don't work any more.
The new syntax in the sbt 0.11.x shell is:
> set logLevel := Level.Warn
Or in your build.sbt file write:
logLevel := Level.WarnWeb application support was split out into a plugin. See the xsbt-web-plugin project.
For an early version of an xsbt Web Start plugin, visit the xsbt-webstart project.
In 0.11, there are three types of project dependencies (classpath, execution, and configuration) and they are independently defined. These were combined in a single dependency type in 0.7.x. A declaration like:
lazy val a = project("a", "A")
lazy val b = project("b", "B", a)meant that the B project had a classpath and execution dependency on A and A had a configuration dependency on B. Specifically, in 0.7.x:
- Classpath: Classpaths for
Awere available on the appropriate classpath forB. - Execution: A task executed on
Bwould be executed onAfirst. - Configuration: For some settings, if they were not overridden in
A, they would default to the value provided inB.
In 0.11, declare the specific type of dependency you want. Read about multi-project builds in the Getting Started Guide for details.
| 0.7 | 0.11 |
|---|---|
| FileUtilities | IO |
| Path class and object |
Path object, File, RichFile
|
| PathFinder class |
Seq[File], PathFinder class, PathFinder object
|
See sbt 0.10 plugins list for a list of currently available plugins.
sbt 0.11 by default suppresses most stack traces and debugging information. It has the nice side effect of giving you less noise on screen, but as a newcomer it can leave you lost for explanation. To see the previous output of a command at a higher verbosity, type last <task> where <task> is the task that failed or that you want to view detailed output for. For example, if you find that your update fails to load all the dependencies as you expect you can enter:
> last update
and it will display the full output from the last run of the update command.
Sometimes sbt doesn't detect that ansi codes aren't supported and you get output that looks like:
[0m[ [0minfo [0m] [0mSet current project to root
or ansi codes are supported but you want to disable colored output. To completely disable ansi codes, set the sbt.log.noformat system property to true. For example,
sbt -Dsbt.log.noformat=true
See the Index of commonly used methods, values, and types. See also the API Documentation and the hyperlinked sources.
See the Index of commonly used methods, values, and types. See also the API Documentation and the hyperlinked sources.
This error occurs when the published checksum, such as a sha1 or md5 hash, differs from the checksum computed for a downloaded artifact, such as a jar or pom.xml. An example of such an error is:
[warn] problem while downloading module descriptor:
http://repo1.maven.org/maven2/commons-fileupload/commons-fileupload/1.2.2/commons-fileupload-1.2.2.pom:
invalid sha1: expected=ad3fda4adc95eb0d061341228cc94845ddb9a6fe computed=0ce5d4a03b07c8b00ab60252e5cacdc708a4e6d8 (1070ms)
The invalid checksum should generally be reported to the repository owner (as was done for the above error). In the meantime, you can temporarily disable checking with the following setting:
checksums in update := NilSee Library Management for details.
sbt runs tests in the same JVM as sbt itself and Scala classes are not in the same class loader as the application classes. Therefore, when using the Scala interpreter, it is important to set it up properly to avoid an error message like:
Failed to initialize compiler: class scala.runtime.VolatileBooleanRef not found.
** Note that as of 2.8 scala does not assume use of the java classpath.
** For the old behavior pass -usejavacp to scala, or if using a Settings
** object programatically, settings.usejavacp.value = true.
The key is to initialize the Settings for the interpreter using embeddedDefaults. For example:
val settings = new Settings
settings.embeddedDefaults[MyType]
val interpreter = new Interpreter(settings, ...)Here, MyType is a representative class that should be included on the interpreter's classpath and in its application class loader. For more background, see the original proposal that resulted in embeddedDefaults being added.
Similarly, use a representative class as the type argument when using the break and breakIf methods of ILoop, as in the following example:
def x(a: Int, b: Int) = {
import scala.tools.nsc.interpreter.ILoop
ILoop.breakIf[MyType](a != b, "a" -> a, "b" -> b )
}