SBT 0.13.x 中的触发执行 [英] Triggered Execution in SBT 0.13.x

问题描述

我正在使用 SBT 0.13.2，我想通过执行编译任务的方式来触发我的任务.我知道我可以通过使用 triggeredBy 方法来实现这一点，如 taskDefinition.triggeredBy(compile in Compile).

I am using SBT 0.13.2 and I want to trigger my task by the way of execution of the compile task. I know that I can achieve this by using the triggeredBy method, as in taskDefinition.triggeredBy(compile in Compile).

我有一个 build.sbt 定义了我的自定义任务.

I have a build.sbt with my custom task defined.

问题是我无法理解为什么以下内容按预期工作

The problem is that I cannot understand why the following works as expected

val triggeredTask = taskKey[Unit]("Triggered by compile")

triggeredTask <<= Def.task {
  println("TRIGGERED BY COMPILE")
}.triggeredBy(compile in Compile)

但下一个不起作用(compile 执行得很好但我的任务没有被触发)

but the next does not work (compile executes just fine but my task is not triggered)

val triggeredTask = taskKey[Unit]("Triggered by compile")

triggeredTask := Def.task {
  println("TRIGGERED BY COMPILE")
}.triggeredBy(compile in Compile).value

我的理解是 SBT 0.13 使 <<= 过时了，:= 应该足够了.

My understanding was that SBT 0.13 made <<= obsolete and := should be sufficient.

推荐答案

我可能误解了你的意思.

I might misunderstand what you are trying to do.

如果我让你的例子更冗长，它会变成这样:

If I make your example more verbose it becomes like this:

val triggeredTaskKey = taskKey[Unit]("Triggered by compile")

val anonymousTask = Def.task {
  println("TRIGGERED BY COMPILE")
}.triggeredBy(compile in Compile)

// I imagine the macro doing something like this
triggeredTaskKey <<= anonymousTask map (identity)

这也不会触发compile上的匿名任务.

This also does not trigger the anonymous task on compile.

请注意，<<= 是提取位置信息的 set 的荣耀版本.而 set 只是 Def.setting(key, value, position) 的别名，它反过来又创建了一个新的 Setting 实例.请注意，内部创建的设置实例具有这三个参数的构造函数.

Note that <<= is a gloried version of set that extracts position information. And set is simply an alias for Def.setting(key, value, position) which in turn creates a new Setting instance. Note that the setting instance that is created internally has a constructor of those 3 parameters.

我认为 sbt 没有办法在没有密钥的情况下声明设置(我可能在这里错了).然而，您似乎想要创建一个没有键的设置(即触发).

I do not think there is a way in sbt to declare a setting without a key (I might be wrong here). It seems however that you want to create a setting (that is triggered) without a key.

这可能是由错误引起的，我不确定 sbt 是否应该递归遍历依赖项以查找在其 info 中具有 triggeredBy 键的任务.然而，它目前不是(如 trigger 方法.

This might be caused by a bug, I am not sure if sbt should recursively walk the dependencies to find tasks that have a triggeredBy key in their info. It currently however is not (as seen in the trigger method.

从理论上讲，您可以通过将正确的触发器绑定到某个任意键来创建设置.我不确定这会如何运作.

Theoretically you could make a work around that creates settings with the correct triggers bound to some arbitrary key. I am not sure how that would work.

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