Reification via a Manifest example

ReifiedManifest.scala

class ReifiedManifest[T <: Any : Manifest](value: T) { 

  val m = manifest[T]   // So at this point we have the manifest for the Parameterized type
                        // At which point we could either do an if() expression on what type is contained in our manifest

  if (m equals manifest[String]) {        
    println("The manifest contains a String")
  } else if (m <:< manifest[AnyVal]) {        // A subtype check using the <:< operation on the Manifest trait
    println("The manifest contains a subtype of AnyVal")
  } else if (m <:< manifest[AnyRef]) {  
    println("The manifest contains a subtype of AnyRef")
  } else {
    println("Not sure what type is contained ?")
  }
  
  // or we could grab the erased type from the manifest and do a match on some attribute of the type              
  
  m.erasure.toString match {
    case "class java.lang.String" => println("ERASURE: pattern matches on a String")
    case "double" | "int"  => println("ERASURE: pattern matches on a Numeric value.")
    case x => println("ERASURE: has picked up another type not spec'd in the pattern match: " + x)
    }
}

new ReifiedManifest("Test")                     // Contains a String  / matches on a String
new ReifiedManifest(1)                          // Contains an AnyVal / matches on a Numeric
new ReifiedManifest(1.2)                        // Contains an AnyVal / matches on a Numeric
new ReifiedManifest(BigDecimal("3.147"))        // Contains an AnyRef / matches on a an unspecified type