scala – 根据设置重新定义sbt任务
发布时间：2020-12-16 10:06:07 所属栏目：安全 来源：网络整理
导读：我想根据设置的值重新定义一个sbt任务.在默认情况下,它应该执行原始任务,在另一种情况下,我想运行自定义任务. 给定任务和设置： val someSetting = Def.settingKey[Boolean]("some setting")val fooTask = Def.taskKey[String]("foo task")someSetting := tr
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我想根据设置的值重新定义一个sbt任务.在默认情况下,它应该执行原始任务,在另一种情况下,我想运行自定义任务.
给定任务和设置： val someSetting = Def.settingKey[Boolean]("some setting")
val fooTask = Def.taskKey[String]("foo task")
someSetting := true
fooTask := {
println("** foo effect **")
"foo value"
}
试图重新定义fooTask： fooTask := {
if( someSetting.value ) fooTask
else Def.task("whatever")
}.value
给出编译错误： build.sbt:39: error: Illegal dynamic dependency
if( someSetting.value ) fooTask
^
使用Def.task任务编译…… fooTask := Def.task {
if( someSetting.value ) fooTask.value
else Def.task("whatever").value
}.value
…但即使someSetting为false也会被执行！ > set someSetting := false [info] Defining *:someSetting [info] The new value will be used by *:fooTask [info] Reapplying settings... > fooTask ** foo effect ** [success] Total time: 1 s,completed Mar 20,2017 11:40:13 PM 试着改用Def.taskDyn …… fooTask := Def.taskDyn {
if( someSetting.value ) fooTask
else Def.task("whatever")
}.value
…导致“在运行时引用未定义的设置”： > set someSetting := true [info] Defining *:someSetting [info] The new value will be used by *:fooTask [info] Reapplying settings... [info] Set current project to sbt-task-games (in build file:/Users/jast/playspace/untitled8/) > fooTask [trace] Stack trace suppressed: run last *:fooTask for the full output. [error] (*:fooTask) sbt.Init$RuntimeUndefined: References to undefined settings at runtime. [error] setting(ScopedKey(Scope(Select(ProjectRef(file:/Users/jast/playspace/untitled8/,untitled8)),Global,Global),fooTask)) at RangePosition(/Users/jast/playspace/untitled8/build.sbt,LineRange(43,47)) referenced from ScopedKey(Scope(Select(ProjectRef(file:/Users/jast/playspace/untitled8/,fooTask) [error] Total time: 0 s,2017 11:49:59 PM 解决方法
在返回执行任务的任务之前,您需要“保存”对实际任务的引用.这就是taskValue的用途：
fooTask := Def.taskDyn {
val default = fooTask.taskValue
if (someSetting.value) Def.task(default.value)
else Def.task("whatever")
}.value
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