Re: Searching for a notion

From:

Patricia Shanahan <pats@acm.org>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 02 Sep 2008 18:56:12 -0700

Message-ID:

<g9kqrs$d98$1@ihnp4.ucsd.edu>

Stefan Ram wrote:

  ?out? is a field of the class ?java.lang.System?,
  ?println? is a method of the object ?java.lang.System.out?.

  Both classes and objects each can have fields and methods.
  Fields and methods of a class are called ?static?,
  fields and methods of an object are called ?non-static? (or so).

  Is there a supernotion for both classes and objects that
  means something like

      ?an entity that can have fields and methods?,

  so that classes and objects are subnotions of this supernotion?

                      ??
                      /\
                  ^ / \ ^
                is-a/ \is-a
                   / \
                  / \
               class object

  (In a sense a class is an object, but is more like a singleton
  with static lifetime. However, a class is not an object in the
  strict JLS sense of the word object, so I can't use ?object?
  for this notion.)

In this sort of context, I would use "Java object" for things that are
specifically designated as objects in the JLS, and "object" for anything
that has fields and methods:

                     object
                       /\
                   ^ / \ ^
                 is-a/ \is-a
                    / \
                   / \
              Java class Java object

Patricia