I have an SBT task that I want available across multiple "parallel" configuration scopes, where the dependencies have scope specifiers automatically applied based on the scope the task is invoked in.
I have something that works--whereby a separate task is instantiated per configuration scope--but it feels clumsy and want to know if there's a better way with less boilerplate.
In my specific use case I'm using sbt-native-packager and defining package preparation tasks with OS-specific settings. Specifically, I'd like to be able to define unpack without specifying the config scope, and then invoke windows:unpack and have the config scope selector appropriately applied to the declared dependencies.
...
// Task and setting definitions
lazy val unpackSrc = settingKey[File]("Name of file we wish to unpack.")
lazy val unpackDstName = settingKey[File]("Unpacking destination.")
lazy val unpack = taskKey[Set[File]]("Unpack `unpackSrc` to `unpackDst`")
...
// OS specific settings via config scopes
unpackSrc in Windows := target.value / "foo-bar-windows.zip"
unpackSrc in Linux := target.value / "foo-bar-linux.zip"
unpackDst in Windows := target.value / "extract" / "windows"
unpackDst in Linux := target.value / "extract" / "linux"
// Task definition.
// This is what I wish I could do, but can't since it assumes global scope:
// unpack <<= (unpackSrc, unpackDst) map { (src, dst) ⇒
// IO.unzip(src, dst)
// }
// Workaround is to create a task generating function...
def unpackTask(conf: Configuration) = Def.task {
val src = (unpackSrc in conf).value
val dst = (unpackDst in conf).value
val s = streams.value
IO.unzip(src, dst)
}
// ... and invoke per configuration.
// This seems clumsy to me, but can't figure out a better way.
unpack in Windows <<= unpackTask(Windows)
unpack in Linux <<= unpackTask(Linux)
Is there some way have defining a task and it's dependencies, and having it work across scopes with proper scope selection?
Related
I am trying to get the information about all modules in my sbt project.
Having the following code
lazy val getModule = taskKey[Module]("get single module info")
lazy val allModules = taskKey[Seq[Module]]("get all modules info")
getModule := Def.task {
Module(name.value, description.value, version.value, organization.value)
}.value,
allModules := Def.task {
val sbtModules = (ThisScope / thisProject).value.aggregate
sbtModules.map { m =>
(ThisScope.in(m) / getModule).value
}
}.value
I'm getting the errors:
[error] problem: Task invocations inside anonymous functions are evaluated independently of whether the anonymous function is invoked or not.
...
[error] /Users/ikryvorotenko/projects/rae/rae-lib/project/SbtToGradlePlugin.scala:27:23: Illegal dynamic reference: m
[error] (ThisScope.in(m) / getModule).value
Does sbt have anything to chain tasks dynamically?
Basically I'm looking for something like Future.sequence for chaining all tasks results into one.
There are a few features described in Tasks that might be helpful.
First, Dynamic Computation with Def.taskDyn allows you to use the result of one task to compute the other. In your case, allModules should be (Def.taskDyn { ... }).value.
To aggregate a task across multiple subprojects etc, you can use ScopeFilter and .all method on a task key.
I am seeing variable declared
lazy val liquibase = TaskKey[Liquibase]("liquibase", "liquibase object")
Then I am seeing this below
liquibase <<= ( liquibaseChangelog, liquibaseDatabase ) map {
( cLog :String, dBase :Database ) =>
new Liquibase( cLog, new FileSystemResourceAccessor, dBase )
}
It looks like its adding functionality to the TaskKey?
In Scala it means nothing, it's a DSL defined by sbt.
In your case what it's doing is defining liquibase in terms of the values assigned to liquibaseChangelog and liquibaseDatabase, therefore adding a dependency on them. See "Computing a value based on other keys' values" for some more detail.
Futhermore, as of sbt 0.13 you can write this in a nicer, clearer way:
liquibase := {
val fs = new FileSystemResourceAccessor
new Liquibase(liquibaseChangelog.value, fs, liquibaseDatabase.value)
}
As a sidenote, you may find SymbolHound handy -- it's a search engine that respects special characters like <<=
the sbt task documentation shows an example of usage dependencies. It is very simple, artificial but it works! So I reproduced it in my project/scala.build without problem.
Note that I choose global scope to make tasks available for any project and any configuration
import sbt._
import Keys._
object TestBuild extends Build {
lazy val sampleTask = taskKey[Int]("A sample task")
lazy val intTask = taskKey[Int]("An int task")
override lazy val settings = super.settings ++ Seq(
intTask := 1 + 2 ,
sampleTask := intTask.value + 1
)
}
Now I'm trying to do something useful and enrich existing sbt key definitions with task that collects compiled class names
import sbt._
import Keys._
import sbt.inc.Analysis
import xsbti.api.ClassLike
import xsbt.api.Discovery.{isConcrete, isPublic}
object TestBuild extends Build {
lazy val debugAPIs = taskKey[List[String]]("list of all top-level definitions")
override lazy val settings = super.settings ++ Seq(
debugAPIs := getAllTop( compile.value )
)
private def getAllTop(analysis : Analysis) : List[String] =
Tests.allDefs(analysis).toList collect {
case c : ClassLike if isConcrete(c) && isPublic(c) => c.name
}
}
Now I get error from sbt:
Reference to undefined setting:
{.}/*:compile from {.}/*:debugAPIs (/home/sbt/project/build.scala:11)
So I have two questions:
How should I define debugAPIs properly so that it task would be available for all projects and all configurations?
How can I reproduce this error in synthetic configuration?
I'm more interested in the second question actually. I look for deep understanding of how sbt works because I'd like to write a plugin for it.
The problem is that you try to access a key value without a proper Scope.
The documentation gives us some hint here.
By default, all the keys associated with compiling, packaging, and
running are scoped to a configuration and therefore may work
differently in each configuration. The most obvious examples are the
task keys compile, package, and run; but all the keys which affect
those keys (such as source-directories or scalac-options or
full-classpath) are also scoped to the configuration.
Let's first focus on a very simple example, which maybe doesn't make much sense, but illustrates the problem. Lets assume that you want to redefine the compile task to itself.
override lazy val settings = super.settings ++ Seq (
compile := { compile.value }
)
Running this in SBT will give you an error, which is more or less like this
[error] {.}/*:compile from {.}/*:compile (/tmp/q-23723818/project/Build.scala:12)
[error] Did you mean compile:compile ?
We didn't specify the scope so SBT picked some defaults. The project was set to ThisBuild (meaning no specific project) and configuration set to Global. The setting was undefined in that context. However it's important to understand that a key is not a setting. The key can exist without scope, but the value of a key is attached to a scope. Note also that, if SBT won't find the value in the requested scope it can delegate to other scopes, but this is another topic.
How can we check this? Turns out that quite simple. Let's ignore the error, and let the SBT start.
If you type inspect compile you'll see that the inspect will look in compile:compile, where the value is defined. We can force it to look in a specific scope, e.g. inspect {.}/*:compile, will look in scope that gave us the error.
> inspect {.}/*:compile
[info] No entry for key.
Indeed it's undefined.
How to solve the issue? You have to give SBT the scope you're looking for. Naively you could try to add a configuration scope.
// this will NOT work
override lazy val settings = super.settings ++ Seq (
compile in Compile := { (compile in Compile).value }
)
Well but there is no global compile, there is only compile per project. You could overcome the issue by not overriding global settings, but the settings for a specific project, and specifying Compile configuration there.
lazy val root = project.in(file(".")).settings(Seq(
compile in Compile := {(compile in Compile).value}
): _*)
This would work,but what if you want to get the compile value regardless of where it is? This is where ScopeFilter comes in handy. Back to your original example. I assume you want to get compile's Analysis object from all the projects.
import sbt._
import Keys._
import sbt.inc.Analysis
import xsbti.api.ClassLike
import xsbt.api.Discovery.{isConcrete, isPublic}
object TestBuild extends Build {
val debugAPIs = taskKey[Seq[String]]("list of all top-level definitions")
val compileInAnyProject = ScopeFilter(inAnyProject, inConfigurations(Compile))
override lazy val settings = super.settings ++ Seq(
debugAPIs := {
getAllTop(compile.all(compileInAnyProject).value)
}
)
private def getAllTop(analyses : Seq[Analysis]) : Seq[String] =
analyses.flatMap { analysis =>
Tests.allDefs(analysis) collect { case c : ClassLike if isConcrete(c) && isPublic(c) => c.name }
}
}
What we created is a ScopeFilter filtering for any project, and in that projects for Compile configuration. Then we looked for all compile values.
You can configure the ScopeFilter to match your needs, and only filter for specific projects/configurations or even tasks. But the key to understand the problem is to remember that in SBT settings are always scoped.
Edit
You have asked how it comes that the compile is not defined globally but is available to every project. This is because there is Defaults.defaultSettings which define it. And each project include it. If you removed super.settings from your Build definition you'd see that among others compile is undefined.
And as if you should do it this way. Well overriding settings in your plugin is in general discouraged in Plugin Best Practices. However I recommend that you read it, together with Plugins chapter. It should give you an idea of how to proceed.
You can also get multiple values from multiple scopes by defining new task returning them. For example to get analyses with a project, you could use following piece of code.
object TestBuild extends Build {
val debugAPIs = taskKey[Seq[(String, String)]]("list of all top-level definitions")
val compileInAnyProject = ScopeFilter(inAnyProject, inConfigurations(Compile))
override lazy val settings = super.settings ++ Seq(
debugAPIs := {
getAllTop(analysisWithProject.all(compileInAnyProject).value)
}
)
lazy val analysisWithProject = Def.task { (thisProject.value, compile.value) }
private def getAllTop(analyses : Seq[(ResolvedProject, Analysis)]) : Seq[(String, String)] =
analyses.flatMap { case (project, analysis) =>
Tests.allDefs(analysis) collect { case c : ClassLike if isConcrete(c) && isPublic(c) => (project.id, c.name) }
}
}
How can you redefine a key in SBT (as opposed to extend or define)?
I currently have the following in my build script (project/build.scala):
fullClasspath in Runtime <<= (fullClasspath in Runtime, classDirectory in Compile) map { (cp, classes) => (cp.files map {
f: File =>
if (f.getName == classes.getName) {
val result = new File(f.getParent + File.separator + "transformed-" + f.getName)
if (result.exists) result else f
} else f
}).classpath }
It extends the classpath in Runtime by adding, for each directory in Compile, a new directory with the same name but with transformed- prepended to the front.
(If you are wondering why, I have a plugin which performs program transformation on the bytecode after compilation but before packaging, and selective recompilation gets very confused if you overwrite the original files.)
My problem is the following: This extends the original key, and therefore the classpath contains the original directories from Compile, plus the renamed copies, but I only want the renamed ones from Compile.
I tried to do something along the lines of
fullClasspath in Runtime := ...
but I don't know what to put on the right-hand side.
I've marked the answer since it lead me directly to the solution, but my final solution was to modify the above code snippet to the following
fullClasspath in Runtime := (fullClasspath in Runtime).value.files.map {
f: File =>
if (f.getName == (classDirectory in Compile).value.getName) {
val result = new File(f.getParent + File.separator + "transformed-" + f.getName)
if (result.exists) result else f
} else f
}.classpath
which does exactly what I wanted, and is slightly better style.
Here's a little experiment I did just now at the sbt command line showing that it's definitely possible to remove something unwanted from fullClasspath:
% sbt
> show runtime:fullClasspath
[info] List(Attributed(.../target/classes),
Attributed(.../jars/scala-library-2.10.4.jar),
Attributed(.../jars/asm-all-3.3.1.jar))
> set fullClasspath in Runtime := (fullClasspath in Runtime).value.files.filterNot(_.getName.containsSlice("asm")).classpath
> show runtime:fullClasspath
[info] List(Attributed(.../target/classes),
Attributed(.../jars/scala-library-2.10.4.jar))
Voila — the "asm-all-3.3.1" entry is gone.
Note that this isn't about <<= vs :=. The latter is just macro-based sugar for the former. The experiment turns out the same if I avoid := and do this instead:
set fullClasspath in Runtime <<= (fullClasspath in Runtime) map
{_.files.filterNot(_.getName.containsSlice("asm")).classpath}
I have the following example build.sbt that uses sbt-assembly. (My assembly.sbt and project/assembly.sbt are set up as described in the readme.)
import AssemblyKeys._
organization := "com.example"
name := "hello-sbt"
version := "1.0"
scalaVersion := "2.10.3"
val hello = taskKey[Unit]("Prints hello")
hello := println(s"hello, ${assembly.value.getName}")
val hey = taskKey[Unit]("Prints hey")
hey <<= assembly map { (asm) => println(s"hey, ${asm.getName}") }
//val hi = taskKey[Unit]("Prints hi")
//hi <<= assembly { (asm) => println(s"hi, $asm") }
Both hello and hey are functionally equivalent, and when I run either task from sbt, they run assembly first and print a message with the same filename. Is there a meaningful difference between the two? (It seems like the definition of hello is "slightly magical", since the dependency on assembly is only implied there, not explicit.)
Lastly, I'm trying to understand why hey needs the map call. Obviously it results in a different object getting passed into asm, but I'm not quite sure how to fix this type error in the definition of hi:
sbt-hello/build.sbt:21: error: type mismatch;
found : Unit
required: sbt.Task[Unit]
hi <<= assembly { (asm) => println(s"hi, $asm") }
^
[error] Type error in expression
It looks like assembly here is a [sbt.TaskKey[java.io.File]][2] but I don't see a map method defined there, so I can't quite figure out what's happening in the type of hey above.
sbt 0.12 syntax vs sbt 0.13 syntax
Is there a meaningful difference between the two?
By meaningful difference, if you mean semantic difference as in observable difference in the behavior of the compiled code, they are the same.
If you mean, any intended differences in code, it's about the style difference between sbt 0.12 syntax sbt 0.13 syntax. Conceptually, I think sbt 0.13 syntax makes it easier to learn and code since you deal with T instead of Initialize[T] directly. Using macro, sbt 0.13 expands x.value into sbt 0.12 equivalent.
anatomy of <<=
I'm trying to understand why hey needs the map call.
That's actually one of the difference macro now is able to handle automatically.
To understand why map is needed in sbt 0.12 style, you need to understand the type of sbt DSL expression, which is Setting[_]. As Getting Started guide puts it:
Instead, the build definition creates a huge list of objects with type Setting[T] where T is the type of the value in the map. A Setting describes a transformation to the map, such as adding a new key-value pair or appending to an existing value.
For tasks, the type of DSL expression is Setting[Task[T]]. To turn a setting key into Setting[T], or to turn a task key into Setting[Task[T]], you use <<= method defined on respective keys. This is implemented in Structure.scala (sbt 0.12 code base has simpler implementation of <<= so I'll be using that as the reference.):
sealed trait SettingKey[T] extends ScopedTaskable[T] with KeyedInitialize[T] with Scoped.ScopingSetting[SettingKey[T]] with Scoped.DefinableSetting[T] with Scoped.ListSetting[T, Id] { ... }
sealed trait TaskKey[T] extends ScopedTaskable[T] with KeyedInitialize[Task[T]] with Scoped.ScopingSetting[TaskKey[T]] with Scoped.ListSetting[T, Task] with Scoped.DefinableTask[T] { ... }
object Scoped {
sealed trait DefinableSetting[T] {
final def <<= (app: Initialize[T]): Setting[T] = setting(scopedKey, app)
...
}
sealed trait DefinableTask[T] { self: TaskKey[T] =>
def <<= (app: Initialize[Task[T]]): Setting[Task[T]] = Project.setting(scopedKey, app)
...
}
}
Note the types of app parameters. Setting key's <<= takes Initialize[T] whereas the task key's <<= takes Initialize[Task[T]]. In other words, depending on the the type of lhs of an <<= expression the type of rhs changes. This requires sbt 0.12 users to be aware of the setting/task difference in the keys.
Suppose you have a setting key like description on the lhs, and suppose you want to depend on name setting and create a description. To create a setting dependency expression you use apply:
description <<= name { n => n + " is good." }
apply for a single key is implemented in Settings.scala:
sealed trait Keyed[S, T] extends Initialize[T]
{
def transform: S => T
final def apply[Z](g: T => Z): Initialize[Z] = new GetValue(scopedKey, g compose transform)
}
trait KeyedInitialize[T] extends Keyed[T, T] {
final val transform = idFun[T]
}
Next, instead of description, suppose you want to create a setting for jarName in assembly. This is a task key, so rhs of <<= takes Initialize[Task[T]], so apply is not good. This is where map comes in:
jarName in assembly <<= name map { n => n + ".jar" }
This is implemented in Structure.scala as well:
final class RichInitialize[S](init: Initialize[S]) {
def map[T](f: S => T): Initialize[Task[T]] = init(s => mktask(f(s)) )
}
Because a setting key extends KeyedInitialize[T], which is Initialize[T], and because there's an implicit conversion from Initialize[T] to RichInitialize[T] the above is available to name. This is an odd way of defining map since maps usually preserves the structure.
It might make more sense, if you see similar enrichment class for task keys:
final class RichInitializeTask[S](i: Initialize[Task[S]]) extends RichInitTaskBase[S, Task] {...}
sealed abstract class RichInitTaskBase[S, R[_]] {
def map[T](f: S => T): Initialize[R[T]] = mapR(f compose successM)
}
So for tasks, map maps from a task of type S to T. For settings, we can think of it as: map is not defined on a setting, so it implicitly converts itself to a task and maps that. In any case, this let's sbt 0.12 users to think: Use apply for settings, map for tasks. Note that apply ever goes away for task keys as they extend Keyed[Task[T], Task[T]]. This should explain:
sbt-hello/build.sbt:21: error: type mismatch;
found : Unit
required: sbt.Task[Unit]
Then there's the tuple issue. So far I've discussed dependencies to a single setting. If you want to depend on more, sbt implicitly adds apply and map to Tuple2..N to handle it. Now it's expanded to 15, but it used to be up till only Tuple9. Seeing from a new user's point of view, the idea of invoking map on a Tuple9 of settings so it generates a task-like Initialize[Task[T]] would appear alien. Without changing the underlying mechanism, sbt 0.13 provides much cleaner surface to get started.