Re: [Jython-users] How to qualify "super"?

[D-Man <ds...@ri...>]

On Mon, Mar 26, 2001 at 09:21:19PM -0500, cindy wrote:
| Hi,
| The book I'm using  to learn Java has a statement
| in one of its examples that is "super(title)".
| This statement is in a module that extends Frame. What
| qualifiers do I need for "super" and what do I have to import?

Java only supports single inheritance.  "super" is a keyword in Java
that refers to a super class of the current class (the first super
class with the specified method).  Here is an example, first in Java
then Python (Jython -- same grammar):

public class MyFrame extends java.awt.Frame
{
    /**
     * A ctor for this class.  Must call Frame's ctor to init it as
     * well.
     */
    public MyFrame( )
    {
        // call java.awt.Frame's ctor
        super( ) ;
    }
}



# bring the "java" module into the current namespace
import java

class MyFrame( java.awt.Frame ) :
    # A initializer (ctor) for this class.  Must call Frame's ctor to
    # init it as well.
    def __init__( self ) :
        # call the java.awt.Frame's ctor
        java.awt.Frame.__init__( self )


The main difference is that Python supports multiple inheritance.
Thus the meaning of "super" in python isn't quite clear and if a
particular meaning is settled on it may not work as expected/intended
in some cases.  As a result python's designers didn't include "super"
as a keyword, but instead you have to specify the super class
explicitly by name.  The end result is the same, just a liitle
different look to the code.

BTW, I just tested the python part, and Jython very nicely translated
the python idiom of calling __init__ into the java ctor of Frame (as
obviously java.awt.Frame doesn't have a method named __init__).

HTH,
-D