Scala - 宏註釋方法調用？

Question

我想寫一個簡單的宏註釋，讓我每次都可以讓方法執行 - 如果我註釋方法定義 - 或者只是這一次，如果我註釋一個方法調用。

註釋方法定義工作得很好。然而，

object Main { 
    def main(args:Array[String]): Unit ={ 
    @MyMacro 
    doTest() //"Hello World" 
    } 
} 

似乎在語法上不正確。因爲intellij抱怨:Unit ={之後它「預計」}，當我刪除@MyMacro時，會有一個警告消失。

註解方法調用（或任意表達式）的正確方法是什麼？

（例如，我可能不會有興趣在獲得定時的到getX所有的電話，但我可能需要測量中的代碼是在一個特定的地點所花費的時間：

val x = @MyMacro getX() 

）

更新

這工作：

object Main { 
    def main(args:Array[String]): Unit ={ 
    hello() 
    } 

    @MyMacro 
    def hello(): Unit ={ 
    println("Hello World") 
    } 
} 

這並不編譯：

object Main { 
    def main(args:Array[String]): Unit ={ 
    hello(): @MyMacro 
    } 

    def hello(): Unit ={ 
    println("Hello World") 
    } 
} 

因爲

Error:(10, 15) macro annotation could not be expanded (the most common reason for that is that you need to enable the macro paradise plugin; another possibility is that you try to use macro annotation in the same compilation run that defines it) 
hello(): @MyMacro 
     ^

我只是用sbt編譯，使用

object BuildSettings { 
    val buildSettings = Defaults.defaultSettings ++ Seq(
    version := "0.0.1", 
    scalaVersion := "2.11.8", 
    scalacOptions += "", 
    crossScalaVersions := Seq("2.10.2", "2.10.3", "2.10.4", "2.10.5", "2.10.6", "2.11.0", "2.11.1", "2.11.2", "2.11.3", "2.11.4", "2.11.5", "2.11.6", "2.11.7", "2.11.8"), 
    resolvers += Resolver.sonatypeRepo("releases"), 
    addCompilerPlugin("org.scalamacros" % "paradise" % "2.1.0" cross CrossVersion.full) 
) 
} 

object ScalaMacroDebugBuild extends Build { 
    import BuildSettings._ 

    lazy val root: Project = Project(
    "root", 
    file("."), 
    settings = buildSettings 
) aggregate(macros, examples) 

    lazy val macros: Project = Project(
    "macros", 
    file("macros"), 
    settings = buildSettings ++ Seq(
     libraryDependencies <+= (scalaVersion)("org.scala-lang" % "scala-compiler" % _)) 
) 

    lazy val examples: Project = Project(
    "examples", 
    file("examples"), 
    settings = buildSettings 
) dependsOn(macros) 
} 

應採取的這兩個問題的關心？

Answer 1

An annotation of an expression e appears after the expression e, separated by a colon.

所以val x = getX(): @MyMacro應該工作。