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The following is a bit inconvenient when sharing code between macro impls and runtime (which would otherwise be nice via passing around an api.Universe):
Welcome to Scala version 2.10.0 (JavaHotSpot(TM) 64-BitServerVM, Java1.7.0_07).
Type in expressions to have them evaluated.
Type:help for more information.
scala>importreflect._importreflect._
scala>classA
defined classA
scala> runtime.universe: api.Universe
res2: scala.reflect.api.Universe= scala.reflect.runtime.JavaUniverse@4ab944df
scala> res2.typeTag[A]
scala.reflect.internal.MissingRequirementError:object$line4.$read not found.
at scala.reflect.internal.MissingRequirementError$.signal(MissingRequirementError.scala:16)
at scala.reflect.internal.MissingRequirementError$.notFound(MissingRequirementError.scala:17)
at scala.reflect.internal.Mirrors$RootsBase.ensureModuleSymbol(Mirrors.scala:126)
at scala.reflect.internal.Mirrors$RootsBase.staticModule(Mirrors.scala:161)
at scala.reflect.internal.Mirrors$RootsBase.staticModule(Mirrors.scala:21)
at $typecreator1$1.apply(<console>:13)
at scala.reflect.api.TypeTags$TypeTag$.apply(TypeTags.scala:302)
at .<init>(<console>:13)
at .<clinit>(<console>)
at .<init>(<console>:7)
at .<clinit>(<console>)
at $print(<console>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethod)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:731)
at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:980)
at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:570)
at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:601)
at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:565)
at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:745)
at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:790)
at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:702)
at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:566)
at scala.tools.nsc.interpreter.ILoop.innerLoop$1(ILoop.scala:573)
at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:576)
at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:867)
at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822)
at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822)
at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135)
at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822)
at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:83)
at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:96)
at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:105)
at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
scala> runtime.universe: api.JavaUniverse
res4: scala.reflect.api.JavaUniverse= scala.reflect.runtime.JavaUniverse@4ab944df
scala> res4.typeTag[A]
res5: res4.TypeTag[A] =TypeTag[A]
The text was updated successfully, but these errors were encountered:
Type tag factory evaluates the provided type creator in the context of the initial mirror in order to maintain referential equality of instances of standard tags. Unfortunately this evaluation might fail if the mirror provided doesn't contain the classes being referred to. Therefore I think we should avoid evaluating type creators there.
Note that failure of evaluation doesn't mean that there's something bad going on. When one creates a type tag, the correct mirror / classloader to interpret that tag in might be unknown (like it happens here). This is okay, and this is exactly what the 2.10.0-M4 refactoring has addressed. Something like res2.typeTag[A].in(currentMirror) is the correct response here.
The following is a bit inconvenient when sharing code between macro impls and runtime (which would otherwise be nice via passing around an api.Universe):
The text was updated successfully, but these errors were encountered: