Add MAinAnnotation Parser and Result type parameters

And remove type members Parser and Result

Author: nicolasstucki

docs/_docs/reference/experimental/main-annotation.md

@@ -31,8 +31,8 @@ object foo {
       ),
       args = args
     )
-    val args0 = cmd.argGetter[Int](0, None) // using cmd.Parser[Int]
-    val args1 = cmd.varargGetter[Int] // using cmd.Parser[Int]
+    val args0 = cmd.argGetter[Int](0, None) // using a parser of Int
+    val args1 = cmd.varargGetter[Int] // using a parser of Int
     cmd.run(() => sum(args0(), args1()*))
   }
 }
@@ -47,17 +47,15 @@ Finally, the `run` method is called to run the application. It receives a by-nam
 Example of implementation of `myMain` that takes all arguments positionally. It used `util.CommandLineParser.FromString` and expects no default arguments. For simplicity, any errors in preprocessing or parsing results in crash.
 
 ```scala
-class myMain extends MainAnnotation:
-  import MainAnnotation.{ ParameterInfo, Command }
-
-  // Parser used to parse command line arguments
-  type Parser[T] = util.CommandLineParser.FromString[T]
+// Parser used to parse command line arguments
+import scala.util.CommandLineParser.FromString[T]
 
-  // Result type of the annotated method
-  type Result = Int
+// Result type of the annotated method is Int
+class myMain extends MainAnnotation[FromString, Int]:
+  import MainAnnotation.{ ParameterInfo, Command }
 
   /** A new command with arguments from `args` */
-  def command(info: CommandInfo, args: Array[String]): Command[Parser, Result] =
+  def command(info: CommandInfo, args: Array[String]): Command[FromString, Int] =
     if args.contains("--help") then
       println(info.documentation)
       // TODO: Print documentation of the parameters
@@ -75,15 +73,15 @@ class myMain extends MainAnnotation:
     new MyCommand(plainArgs, varargs)
 
   @experimental
-  class MyCommand(plainArgs: Seq[String], varargs: Seq[String]) extends Command[util.CommandLineParser.FromString, Int]:
+  class MyCommand(plainArgs: Seq[String], varargs: Seq[String]) extends Command[FromString, Int]:
 
-    def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using parser: Parser[T]): () => T =
+    def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using parser: FromString[T]): () => T =
       () => parser.fromString(plainArgs(idx))
 
-    def varargGetter[T](using parser: Parser[T]): () => Seq[T] =
+    def varargGetter[T](using parser: FromString[T]): () => Seq[T] =
       () => varargs.map(arg => parser.fromString(arg))
 
-    def run(program: () => Result): Unit =
+    def run(program: () => Int): Unit =
       println("executing program")
       val result = program()
       println("result: " + result)

library/src/scala/annotation/MainAnnotation.scala

@@ -40,19 +40,14 @@ package scala.annotation
  *    }
  *  }
  *  ```
+ *
+ *  @param Parser The class used for argument string parsing and arguments into a `T`
+ *  @param Result The required result type of the main method.
+ *                If this type is Any or Unit, any type will be accepted.
  */
 @experimental
-trait MainAnnotation extends StaticAnnotation:
-  import MainAnnotation.*
-
-  /** The class used for argument string parsing and arguments into a `T` */
-  type Parser[T]
-
-  /** The required result type of the main method.
-   *
-   *  If this type is Any or Unit, any type will be accepted.
-   */
-  type Result
+trait MainAnnotation[Parser[_], Result] extends StaticAnnotation:
+  import MainAnnotation.{Command, CommandInfo}
 
   /** A new command with arguments from `args`
    *

tests/run/main-annotation-example.scala

@@ -1,5 +1,6 @@
 import scala.annotation.*
 import collection.mutable
+import scala.util.CommandLineParser.FromString
 
 /** Sum all the numbers
  *
@@ -20,17 +21,11 @@ object Test:
 end Test
 
 @experimental
-class myMain extends MainAnnotation:
+class myMain extends MainAnnotation[FromString, Int]:
   import MainAnnotation.{ Command, CommandInfo, ParameterInfo }
 
-  // Parser used to parse command line arguments
-  type Parser[T] = util.CommandLineParser.FromString[T]
-
-  // Result type of the annotated method
-  type Result = Int
-
   /** A new command with arguments from `args` */
-  def command(info: CommandInfo, args: Array[String]): Command[Parser, Result] =
+  def command(info: CommandInfo, args: Array[String]): Command[FromString, Int] =
     if args.contains("--help") then
       println(info.documentation)
       System.exit(0)
@@ -47,15 +42,15 @@ class myMain extends MainAnnotation:
     new MyCommand(plainArgs, varargs)
 
   @experimental
-  class MyCommand(plainArgs: Seq[String], varargs: Seq[String]) extends Command[util.CommandLineParser.FromString, Int]:
+  class MyCommand(plainArgs: Seq[String], varargs: Seq[String]) extends Command[FromString, Int]:
 
-    def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using parser: Parser[T]): () => T =
+    def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using parser: FromString[T]): () => T =
       () => parser.fromString(plainArgs(idx))
 
-    def varargGetter[T](using parser: Parser[T]): () => Seq[T] =
+    def varargGetter[T](using parser: FromString[T]): () => Seq[T] =
       () => varargs.map(arg => parser.fromString(arg))
 
-    def run(program: () => Result): Unit =
+    def run(program: () => Int): Unit =
       println("executing program")
       val result = program()
       println("result: " + result)

tests/run/main-annotation-homemade-annot-1.scala

@@ -3,6 +3,7 @@ import scala.annotation.*
 import scala.collection.mutable
 import ExecutionContext.Implicits.global
 import duration._
+import util.CommandLineParser.FromString
 
 @mainAwait def get(wait: Int): Future[Int] = Future{
   Thread.sleep(1000 * wait)
@@ -28,20 +29,17 @@ object Test:
 end Test
 
 @experimental
-class mainAwait(timeout: Int = 2) extends MainAnnotation:
+class mainAwait(timeout: Int = 2) extends MainAnnotation[FromString, Future[Any]]:
   import MainAnnotation.*
 
-  override type Parser[T] = util.CommandLineParser.FromString[T]
-  override type Result = Future[Any]
-
   // This is a toy example, it only works with positional args
-  def command(info: CommandInfo, args: Array[String]): Command[Parser, Result] =
-    new Command[Parser, Result]:
-      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: Parser[T]): () => T =
+  def command(info: CommandInfo, args: Array[String]): Command[FromString, Future[Any]] =
+    new Command[FromString, Future[Any]]:
+      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: FromString[T]): () => T =
         () => p.fromString(args(idx))
 
-      override def varargGetter[T](using p: Parser[T]): () => Seq[T] =
+      override def varargGetter[T](using p: FromString[T]): () => Seq[T] =
         () => for i <- ((info.parameters.length-1) until args.length) yield p.fromString(args(i))
 
-      override def run(f: () => Result): Unit = println(Await.result(f(), Duration(timeout, SECONDS)))
+      override def run(f: () => Future[Any]): Unit = println(Await.result(f(), Duration(timeout, SECONDS)))
 end mainAwait

tests/run/main-annotation-homemade-annot-2.scala

@@ -1,5 +1,6 @@
 import scala.collection.mutable
 import scala.annotation.*
+import util.CommandLineParser.FromString
 
 @myMain()("A")
 def foo1(): Unit = println("I was run!")
@@ -28,22 +29,19 @@ end Test
 
 // This is a toy example, it only works with positional args
 @experimental
-class myMain(runs: Int = 3)(after: String*) extends MainAnnotation:
+class myMain(runs: Int = 3)(after: String*) extends MainAnnotation[FromString, Any]:
   import MainAnnotation.*
 
-  override type Parser[T] = util.CommandLineParser.FromString[T]
-  override type Result = Any
+  def command(info: CommandInfo, args: Array[String]): Command[FromString, Any] =
+    new Command[FromString, Any]:
 
-  def command(info: CommandInfo, args: Array[String]): Command[Parser, Result] =
-    new Command[Parser, Result]:
-
-      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: Parser[T]): () => T =
+      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: FromString[T]): () => T =
         () => p.fromString(args(idx))
 
-      override def varargGetter[T](using p: Parser[T]): () => Seq[T] =
+      override def varargGetter[T](using p: FromString[T]): () => Seq[T] =
         () => for i <- (info.parameters.length until args.length) yield p.fromString(args(i))
 
-      override def run(f: () => Result): Unit =
+      override def run(f: () => Any): Unit =
         for (_ <- 1 to runs)
           f()
           if after.length > 0 then println(after.mkString(", "))

tests/run/main-annotation-homemade-annot-3.scala

@@ -1,4 +1,5 @@
 import scala.annotation.*
+import scala.util.CommandLineParser.FromString
 
 @mainNoArgs def foo() = println("Hello world!")
 
@@ -10,17 +11,14 @@ object Test:
 end Test
 
 @experimental
-class mainNoArgs extends MainAnnotation:
+class mainNoArgs extends MainAnnotation[FromString, Any]:
   import MainAnnotation.*
 
-  override type Parser[T] = util.CommandLineParser.FromString[T]
-  override type Result = Any
+  def command(info: CommandInfo, args: Array[String]): Command[FromString, Any] =
+    new Command[FromString, Any]:
+      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: FromString[T]): () => T = ???
 
-  def command(info: CommandInfo, args: Array[String]): Command[Parser, Result] =
-    new Command[Parser, Result]:
-      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: Parser[T]): () => T = ???
+      override def varargGetter[T](using p: FromString[T]): () => Seq[T] = ???
 
-      override def varargGetter[T](using p: Parser[T]): () => Seq[T] = ???
-
-      override def run(program: () => Result): Unit = program()
+      override def run(program: () => Any): Unit = program()
   end command

tests/run/main-annotation-homemade-annot-4.scala

@@ -1,4 +1,5 @@
 import scala.annotation.*
+import scala.util.CommandLineParser.FromString
 
 @mainManyArgs(1, "B", 3) def foo() = println("Hello world!")
 
@@ -10,17 +11,14 @@ object Test:
 end Test
 
 @experimental
-class mainManyArgs(i1: Int, s2: String, i3: Int) extends MainAnnotation:
+class mainManyArgs(i1: Int, s2: String, i3: Int) extends MainAnnotation[FromString, Any]:
   import MainAnnotation.*
 
-  override type Parser[T] = util.CommandLineParser.FromString[T]
-  override type Result = Any
+  def command(info: CommandInfo, args: Array[String]): Command[FromString, Any] =
+    new Command[FromString, Any]:
+      override def argGetter[T](idx: Int, optDefaultGetter: Option[() => T])(using p: FromString[T]): () => T = ???
 
-  def command(info: CommandInfo, args: Array[String]): Command[Parser, Result] =
-    new Command[Parser, Result]:
-      override def argGetter[T](idx: Int, optDefaultGetter: Option[() => T])(using p: Parser[T]): () => T = ???
+      override def varargGetter[T](using p: FromString[T]): () => Seq[T] = ???
 
-      override def varargGetter[T](using p: Parser[T]): () => Seq[T] = ???
-
-      override def run(program: () => Result): Unit = program()
+      override def run(program: () => Any): Unit = program()
   end command

tests/run/main-annotation-homemade-annot-5.scala

@@ -1,4 +1,5 @@
 import scala.annotation.*
+import scala.util.CommandLineParser.FromString
 
 @mainManyArgs(Some(1)) def foo() = println("Hello world!")
 @mainManyArgs(None) def bar() = println("Hello world!")
@@ -12,17 +13,14 @@ object Test:
 end Test
 
 @experimental
-class mainManyArgs(o: Option[Int]) extends MainAnnotation:
+class mainManyArgs(o: Option[Int]) extends MainAnnotation[FromString, Any]:
   import MainAnnotation.*
 
-  override type Parser[T] = util.CommandLineParser.FromString[T]
-  override type Result = Any
+  def command(info: CommandInfo, args: Array[String]): Command[FromString, Any] =
+    new Command[FromString, Any]:
+      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: FromString[T]): () => T = ???
 
-  def command(info: CommandInfo, args: Array[String]): Command[Parser, Result] =
-    new Command[Parser, Result]:
-      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: Parser[T]): () => T = ???
+      override def varargGetter[T](using p: FromString[T]): () => Seq[T] = ???
 
-      override def varargGetter[T](using p: Parser[T]): () => Seq[T] = ???
-
-      override def run(program: () => Result): Unit = program()
+      override def run(program: () => Any): Unit = program()
   end command

tests/run/main-annotation-homemade-annot-6.scala

@@ -17,13 +17,10 @@ object Test:
 end Test
 
 @experimental
-class myMain extends MainAnnotation:
+class myMain extends MainAnnotation[Make, Any]:
   import MainAnnotation.*
 
-  override type Parser[T] = Make[T]
-  override type Result = Any
-
-  def command(info: CommandInfo, args: Array[String]): Command[Parser, Result] =
+  def command(info: CommandInfo, args: Array[String]): Command[Make, Any] =
     def paramInfoString(paramInfo: ParameterInfo) =
       import paramInfo.*
       s"    ParameterInfo(name=\"$name\", typeName=\"$typeName\", hasDefault=$hasDefault, isVarargs=$isVarargs, documentation=\"$documentation\", annotations=$annotations)"
@@ -34,16 +31,16 @@ class myMain extends MainAnnotation:
          |  "${info.documentation}",
          |  ${info.parameters.map(paramInfoString).mkString("Seq(\n", ",\n", "\n  )*")}
          |)""".stripMargin)
-    new Command[Parser, Result]:
-      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: Parser[T]): () => T =
+    new Command[Make, Any]:
+      override def argGetter[T](idx: Int, defaultArgument: Option[() => T])(using p: Make[T]): () => T =
         println(s"argGetter($idx, ${defaultArgument.map(_())})")
         () => p.make
 
-      override def varargGetter[T](using p: Parser[T]): () => Seq[T] =
+      override def varargGetter[T](using p: Make[T]): () => Seq[T] =
         println("varargGetter()")
         () => Seq(p.make, p.make)
 
-      override def run(f: () => Result): Unit =
+      override def run(f: () => Any): Unit =
         println("run()")
         f()
         println()

tests/run/main-annotation-newMain.scala

@@ -1,5 +1,6 @@
 import scala.annotation.*
 import collection.mutable
+import scala.util.CommandLineParser.FromString
 
 @newMain def happyBirthday(age: Int, name: String, others: String*) =
   val suffix =
@@ -29,15 +30,12 @@ end Test
 
 
 @experimental
-final class newMain extends MainAnnotation:
+final class newMain extends MainAnnotation[FromString, Any]:
   import newMain._
   import MainAnnotation._
 
-  override type Parser[T] = util.CommandLineParser.FromString[T]
-  override type Result = Any
-
-  def command(info: CommandInfo, args: Array[String]): Command[Parser, Result] =
-    new Command[Parser, Result]:
+  def command(info: CommandInfo, args: Array[String]): Command[FromString, Any] =
+    new Command[FromString, Any]:
 
       private inline val argMarker = "--"
       private inline val shortArgMarker = "-"
@@ -133,7 +131,7 @@ final class newMain extends MainAnnotation:
         case s => argMarker + s
       }
 
-      private def convert[T](argName: String, arg: String)(using p: Parser[T]): () => T =
+      private def convert[T](argName: String, arg: String)(using p: FromString[T]): () => T =
         p.fromStringOption(arg) match
           case Some(t) => () => t
           case None => error(s"invalid argument for $argName: $arg")
@@ -233,7 +231,7 @@ final class newMain extends MainAnnotation:
       private def getInvalidNames(paramInfos: ParameterInfo): Seq[String | Char] =
         getAliases(paramInfos).filter(name => !nameIsValid(name) && !shortNameIsValid(name))
 
-      override def argGetter[T](idx: Int, optDefaultGetter: Option[() => T])(using p: Parser[T]): () => T =
+      override def argGetter[T](idx: Int, optDefaultGetter: Option[() => T])(using p: FromString[T]): () => T =
         val name = info.parameters(idx).name
         val parameterInfo = nameToParameterInfo(name)
         // TODO: Decide which string is associated with this arg when constructing the command.
@@ -259,7 +257,7 @@ final class newMain extends MainAnnotation:
         }
       end argGetter
 
-      override def varargGetter[T](using p: Parser[T]): () => Seq[T] =
+      override def varargGetter[T](using p: FromString[T]): () => Seq[T] =
         val name = info.parameters.last.name
         // TODO: Decide which strings are associated with the varargs when constructing the command.
         //       Here we should only get the strings for this argument, apply them to the parser and handle parsing errors.
@@ -269,7 +267,7 @@ final class newMain extends MainAnnotation:
         // First take arguments passed by name, then those passed by position
         () => (byNameGetters ++ positionalGetters).map(_())
 
-      override def run(f: () => Result): Unit =
+      override def run(f: () => Any): Unit =
         // Check aliases unicity
         val nameAndCanonicalName = nameToParameterInfo.toList.flatMap {
           case (canonicalName, infos) => (canonicalName +: getAlternativeNames(infos) ++: getShortNames(infos)).map(_ -> canonicalName)