doLast和leftShift在Gradle任务上的区别？ [英] Difference between doLast and leftShift on Gradle task?

问题描述

我意识到传递配置闭包和定义任务动作之间的区别。我相信你不能在配置闭包中使用<< ，因为它看起来像是一个语法错误：

I am aware of the difference between passing in a configuration closure and defining an action for a task. I believe you can't use << in a configuration closure because it seems like a syntax error:

task wrong {
  << { println "From doLast" }
}

但是。为什么我不能在上面的配置闭包中使用 leftShift 作为<< 的等价物？在一个更清晰的测试案例中，为什么下面的buildfile不会输出 from leftShift - inside ？

But. Why can't I use leftShift as an equivalent of << in the above configuration closure? In an even more clear test case, why doesn't the following buildfile output the line From leftShift - inside?

defaultTasks 'tryout'

task tryout {
  doLast { println "From doLast" }
  leftShift { println "From leftShift - inside" }
}

tryout.leftShift { println "From leftShift - outside" }

当然，这不是一个真正的问题，因为我可以简单地使用doLast。我只是想扩大我对Gradle的理解。当与任务定义一起使用时，感谢！

Of course, this is not a real problem, as I can simply use doLast. I'm just trying to broaden my understanding of Gradle. Thanks!

推荐答案

<< ，而不是真的是按位意义上的左移。它是 doLast 的简写。在gradle DSL中：

<< when used with a task definition, is not really a leftshift in the bitwise sense. It is shorthand for doLast. In gradle DSL:

task hello << {
    println 'Hello world!'
}

完全相同：

task hello {
    doLast{
        println 'Hello world!'
    }
}

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