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Python was designed (was Re: Multi-threading in Python vs Java)

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  Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-13 09:37 +1100
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-13 03:38 +0000
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-13 15:34 +1100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Roy Smith <roy@panix.com> - 2013-10-13 09:04 -0400
        Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-14 03:39 -0700
    Re: Python was designed (was Re: Multi-threading in Python vs Java) John Nagle <nagle@animats.com> - 2013-10-14 12:18 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-15 09:43 +1100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-15 10:11 +1100
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve@pearwood.info> - 2013-10-15 08:50 +0000
          Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-15 08:48 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-14 18:31 -0700
        Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-14 20:02 -0700
          Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-15 13:26 -0700
            Re: Python was designed (was Re: Multi-threading in Python vs Java) Grant Edwards <invalid@invalid.invalid> - 2013-10-15 21:46 +0000
              Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-16 10:45 -0700
                Re: Python was designed (was Re: Multi-threading in Python vs Java) Grant Edwards <invalid@invalid.invalid> - 2013-10-16 18:42 +0000
            Re: Python was designed (was Re: Multi-threading in Python vs Java) "Rhodri James" <rhodri@wildebst.demon.co.uk> - 2013-10-15 23:01 +0100
              Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-15 21:45 -0700
              Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-16 10:57 -0700
                Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-16 11:25 -0700
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Skip Montanaro <skip@pobox.com> - 2013-10-16 13:49 -0500
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-17 07:40 +1100
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-16 17:13 -0700
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-17 11:28 +1100
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Ned Batchelder <ned@nedbatchelder.com> - 2013-10-16 20:47 -0400
                    Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-16 18:30 -0700
                      Re: Python was designed (was Re: Multi-threading in Python vs Java) Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-10-17 11:20 +0300
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-16 17:53 -0700
                    Re: Python was designed Piet van Oostrum <piet@vanoostrum.org> - 2013-10-16 22:33 -0400
                    Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve@pearwood.info> - 2013-10-17 05:24 +0000
                    Re: Python was designed (was Re: Multi-threading in Python vs Java) Grant Edwards <invalid@invalid.invalid> - 2013-10-17 13:43 +0000
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-17 12:01 +1100
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Ned Batchelder <ned@nedbatchelder.com> - 2013-10-16 22:09 -0400
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-17 08:02 +0100
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-17 07:49 -0700
                    Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-18 01:52 +0000
                      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-17 19:08 -0700
                        Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-17 20:34 -0700
                        Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-18 03:56 +0000
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-18 02:00 +1100
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-17 16:00 +0100
                Re: Python was designed (was Re: Multi-threading in Python vs Java) Grant Edwards <invalid@invalid.invalid> - 2013-10-16 18:44 +0000
                Re: Python was designed (was Re: Multi-threading in Python vs Java) alex23 <wuwei23@gmail.com> - 2013-10-17 10:26 +1000
            Re: Python was designed Piet van Oostrum <piet@vanoostrum.org> - 2013-10-15 23:20 -0400
            Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-15 20:53 -0700
            Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-17 10:32 -0700
              Re: Python was designed (was Re: Multi-threading in Python vs Java) MRAB <python@mrabarnett.plus.com> - 2013-10-17 18:44 +0100
                Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-17 20:15 -0700
              Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-17 19:08 +0100
              Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-17 12:49 -0700
              Re: Python was designed (was Re: Multi-threading in Python vs Java) Ned Batchelder <ned@nedbatchelder.com> - 2013-10-17 16:57 -0400
              Re: Python was designed (was Re: Multi-threading in Python vs Java) Ethan Furman <ethan@stoneleaf.us> - 2013-10-17 15:10 -0700
              Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-17 18:59 -0700
                Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-18 02:57 +0000
          Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-15 23:48 +0100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Terry Reedy <tjreedy@udel.edu> - 2013-10-14 21:35 -0400
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Roy Smith <roy@panix.com> - 2013-10-14 21:50 -0400
          Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-15 08:21 +0100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-15 12:48 +1100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Janssen <dreamingforward@gmail.com> - 2013-10-14 19:11 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-15 13:19 +1100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-15 03:18 +0000
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-15 14:29 +1100
        Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-14 20:48 -0700
          Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve@pearwood.info> - 2013-10-15 05:51 +0000
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-10-15 09:48 +0200
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-15 19:57 +1100
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-15 15:01 +0000
          Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-16 06:09 +1100
          Re: Python was designed (was Re: Multi-threading in Python vs Java) Tim Chase <python.list@tim.thechases.com> - 2013-10-15 16:17 -0500
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-10-15 12:26 +0200
      Re: Python was designed (was Re: Multi-threading in Python vs Java) wxjmfauth@gmail.com - 2013-10-15 13:11 -0700
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-15 22:00 +0100
          Re: Python was designed (was Re: Multi-threading in Python vs Java) wxjmfauth@gmail.com - 2013-10-24 23:14 -0700
            Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-25 19:05 +0100
              Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-26 04:46 +0000
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-14 14:11 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-14 22:43 +0100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-15 09:45 +1100
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-15 17:18 -0700
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-16 23:49 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-17 18:15 +1100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-17 05:39 -0700
        Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-17 06:00 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Terry Reedy <tjreedy@udel.edu> - 2013-10-17 16:15 -0400
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-17 21:41 +0100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-18 03:14 +0000
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-18 15:12 +1100
          Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-18 04:45 +0000
            Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-18 15:53 +1100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-19 09:57 +0000
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-19 21:49 +1100
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-17 00:23 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Christian Gollwitzer <auriocus@gmx.de> - 2013-10-17 09:42 +0200
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-17 19:24 +1100
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-18 01:58 +0000
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Piet van Oostrum <piet@vanoostrum.org> - 2013-10-17 12:58 -0400
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-17 12:37 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Roy Smith <roy@panix.com> - 2013-10-17 20:01 -0400
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-18 11:09 +1100
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-17 13:54 -0700
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-18 13:32 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-18 21:41 +0100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-18 22:26 -0700
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-19 16:35 +1100
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-21 02:07 +0000
          Re: Python was designed (was Re: Multi-threading in Python vs Java) Roy Smith <roy@panix.com> - 2013-10-20 22:21 -0400
            Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-20 21:44 -0700
          Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-21 17:56 +1100
            Re: Python was designed (was Re: Multi-threading in Python vs Java) Roy Smith <roy@panix.com> - 2013-10-21 09:05 -0400
              Re: Python was designed (was Re: Multi-threading in Python vs Java) Lele Gaifax <lele@metapensiero.it> - 2013-10-22 09:38 +0200
                Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve@pearwood.info> - 2013-10-23 08:16 +0000
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Ned Batchelder <ned@nedbatchelder.com> - 2013-10-23 06:36 -0400
                    Re: Python was designed (was Re: Multi-threading in Python vs Java) Grant Edwards <invalid@invalid.invalid> - 2013-10-23 14:21 +0000
                  Re: Python was designed (was Re: Multi-threading in Python vs Java) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2013-10-24 00:31 +1300
                    Re: Python was designed (was Re: Multi-threading in Python vs Java) Lele Gaifax <lele@metapensiero.it> - 2013-10-23 17:56 +0200
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-18 13:56 -0700
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-20 23:44 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-21 18:01 +1100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-21 08:27 +0100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-21 18:31 +1100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-21 08:39 +0100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-21 18:43 +1100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-21 09:11 +0100
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve@pearwood.info> - 2013-10-21 08:24 +0000
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Metallicow <metaliobovinus@gmail.com> - 2013-10-21 01:39 -0700
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-21 01:43 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Metallicow <metaliobovinus@gmail.com> - 2013-10-21 02:17 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-21 05:50 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-22 02:29 +0000
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Skip Montanaro <skip@pobox.com> - 2013-10-22 07:02 -0500
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Metallicow <metaliobovinus@gmail.com> - 2013-10-23 22:31 -0700
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-21 19:55 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) rusi <rustompmody@gmail.com> - 2013-10-21 20:19 -0700
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-22 17:13 +1100
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-22 00:51 -0700
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-25 01:12 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-26 06:19 +0000
        Re: Python was designed (was Re: Multi-threading in Python vs Java) Chris Angelico <rosuav@gmail.com> - 2013-10-26 17:36 +1100
      Re: Python was designed Paul Rubin <no.email@nospam.invalid> - 2013-10-26 10:36 -0700
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-25 23:59 -0700
    Re: Python was designed (was Re: Multi-threading in Python vs Java) Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-26 12:24 -0700
      Re: Python was designed (was Re: Multi-threading in Python vs Java) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-26 22:31 +0100

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#56938

I don't know if I want to step into the flames here, but my understanding has always been that in the absence of polymorphism the best you can do is "object based" programming instead of "object oriented" programming.

Object based programming is a powerful step forward. The insight that by associating data structures and methods together you can significantly improve readability and robustness. 

Object oriented programming takes things further, most significantly by introducing the idea that the object reference you are referencing might be a run time dependent sub-class. Even Python, which isn't strongly typed, manages polymorphism by allowing the self argument to a sub-class of the method class.

There are many wonderful examples of object based programming in C. I believe VB (not VB.net, the older VBA language) is object based but not object oriented. 

True object oriented programming seems to require proper support from the language itself, because the run-time resolution of the "this/self" reference needs specific constructs in the language. 

Bear in mind that my usual disclaimer when wading into the flames like this is to quote Randy Newman ... "I may be wrong .... but I don't think so!!"

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#56941

On Thu, Oct 17, 2013 at 5:49 PM, Peter Cacioppi
<peter.cacioppi@gmail.com> wrote:
> I don't know if I want to step into the flames here, but my understanding has always been that in the absence of polymorphism the best you can do is "object based" programming instead of "object oriented" programming.
>
> Object oriented programming takes things further, most significantly by introducing the idea that the object reference you are referencing might be a run time dependent sub-class. Even Python, which isn't strongly typed, manages polymorphism by allowing the self argument to a sub-class of the method class.

What you've said here is that "without polymorphism, you can't have
polymorphism". :)

The OS/2 PM with SOM (System Object Model) classes does give
polymorphic functionality; here's a bit of an example:

(Reference: http://www.markcrocker.com/rexxtipsntricks/rxtt28.2.0299.html
- class hierarchy, standard classes only)

Part way down you'll see WPFolder. It's a subclass of WPFileSystem
(aka "stuff backed by the disk" as opposed to abstract objects), which
is a subclass of WPObject (aka "stuff you can see and click on"),
which is a subclass of SOMObject (aka "stuff"). The WPFolder class
defines a whole pile of functionality, and its code is all stored in
some library somewhere, as a binary on the disk. Well and good.

Now look at the WPRootFolder class. It's a subclass of WPFolder and
adds a few extra bits and bobs designed for the root of any particular
drive (OS/2 uses an MS-DOS style of drive letters for volumes, rather
than a Unix-style mount points) - menu items for formatting the drive,
getting extra info perhaps, whatever. But most of its functionality
comes from WPFolder.

When a WPFolder method is called on a WPRootFolder, the code has to
handle the fact that it's working with a subclass of that object. As
long as the proper SOM boilerplate is maintained correctly, the
WPFolder code won't even be aware that it's operating on a
WPRootFolder. That's polymorphism, and it's all done in a completely
cross-language way :)

(There are additional complications, as it's possible for a subclass
to WPReplaceClass (I'm probably misremembering the function name)
itself into the position of the parent class, which messes up the
hierarchy a bit - it still all works, but it's less clean to describe.
Most things work the way I'm describing.)

ChrisA

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#56956

On Thursday, October 17, 2013 12:19:02 PM UTC+5:30, Peter Cacioppi wrote:
> Object oriented programming takes things further, most significantly by introducing the idea that the object reference you are referencing might be a run time dependent sub-class. Even Python, which isn't strongly typed, manages polymorphism by allowing the self argument to a sub-class of the method class.

Yes and the reference I earlier gave was just for that:
http://lwn.net/Articles/444910/

Ironically he describes the whole 'polymorphism-in-C' infrastructure there but does not call it that.
The first line however in the sequel article http://lwn.net/Articles/446317/
does just that. Heres the quote:

--------------------
In the first part of this analysis we looked at how the polymorphic side of object-oriented programming was implemented in the Linux kernel using regular C constructs. In particular we examined method dispatch, looked at the different forms that vtables could take, and the circumstances where separate vtables were eschewed in preference for storing function pointers directly in objects. In this conclusion we will explore a second important aspect of object-oriented programming - inheritance, and in particular data inheritance.
--------------------

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#56957

On Thursday, October 17, 2013 6:09:59 PM UTC+5:30, rusi wrote:
> On Thursday, October 17, 2013 12:19:02 PM UTC+5:30, Peter Cacioppi wrote:
> 
> > Object oriented programming takes things further, most significantly by 
> introducing the idea that the object reference you are referencing might be a 
> run time dependent sub-class. Even Python, which isn't strongly typed, 
> manages polymorphism by allowing the self argument to a sub-class of the 
> method class.
> 
> 
> Yes and the reference I earlier gave was just for that:
> http://lwn.net/Articles/444910/
> 
> Ironically he describes the whole 'polymorphism-in-C' infrastructure there but does not call it that.
> 
> The first line however in the sequel article http://lwn.net/Articles/446317/
> does just that. Heres the quote:

I would be a bit remiss if I left it at that -- yeah Mark is clueless about his history and philosophy.  However the general usage of the word polymorphism in the OOP community is not much better.

Cardelli and Wegner:
http://lucacardelli.name/Papers/OnUnderstanding.A4.pdf
give a conspectus of the field.  Especially section 1.3 shows that the word can mean one of 4 very different and unrelated ideas.

OOP aficionados think one of them to be the only one. 

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#56989

On 10/17/2013 2:49 AM, Peter Cacioppi wrote:

>  Even Python, which isn't strongly typed,

Python objects have a definite type/class.  It is fixed for instances of 
builtins. If that is not 'strong', the word has no meaning.

> manages polymorphism by allowing the self argument to a sub-class of the method class.

???

-- 
Terry Jan Reedy

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#56990

On 17/10/2013 07:49, Peter Cacioppi wrote:
> I don't know if I want to step into the flames here,
>Even Python, which isn't strongly typed
>

Yeah right.

-- 
Roses are red,
Violets are blue,
Most poems rhyme,
But this one doesn't.

Mark Lawrence

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#57021

On Wed, 16 Oct 2013 23:49:02 -0700, Peter Cacioppi wrote:

> Even Python, which isn't strongly typed

I see that in a later message you have stepped away from that 
misconception, but I think it is well worth reading this essay:

https://cdsmith.wordpress.com/2011/01/09/an-old-article-i-wrote/

previously known as "What To Know Before Debating Type Systems".


I think the author goes a little too far to claim that "strong" and 
"weak" are meaningless terms when it comes to type systems. I think it is 
quite reasonable to accept that there is no hard and fast line dividing 
"strongly" and "weakly" typed languages, without concluding that the 
terms are meaningless. I think it is reasonable to say that Haskell has a 
very strong type system, since it will (almost?) never allow any 
operation on an unexpected type, or automatically convert one type to 
another. Pascal is a little weaker, since it will automatically convert 
numeric types but nothing else. Perl and PHP are a lot weaker, since they 
will convert strings to numbers and vice versa. If you want to draw the 
line between "strong" and "weak" so that Pascal is on one side and Perl 
on the other, that seems reasonable to me.

One thing he missed is that there are untyped languages where everything 
is the same type. If everything is the same type, that's equivalent to 
there being no types at all. Examples include TCL and Hypertalk, where 
everything are strings, and Forth, where everything are two-byte words.

But I digress. Apart from those couple of little criticisms, I think it 
is a very useful article to read.



-- 
Steven

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#57029

On Fri, Oct 18, 2013 at 2:14 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> One thing he missed is that there are untyped languages where everything
> is the same type. If everything is the same type, that's equivalent to
> there being no types at all. Examples include TCL and Hypertalk, where
> everything are strings, and Forth, where everything are two-byte words.
>
> But I digress. Apart from those couple of little criticisms, I think it
> is a very useful article to read.

Continuing the digression slightly: If everything's a string, how do
you handle aggregate types like arrays? Are they outside the type
system altogether (like in C, where an array-of-int isn't something
you can pass around, though pointer-to-int is)? The only language I've
worked with that has "everything is strings" is REXX, and it does some
fancy footwork with variable names to do mappings, with a general
convention around the use of stem.0 to create ersatz arrays (probably
how JavaScript got the idea).

ChrisA

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#57031

On Fri, 18 Oct 2013 15:12:36 +1100, Chris Angelico wrote:

> On Fri, Oct 18, 2013 at 2:14 PM, Steven D'Aprano
> <steve+comp.lang.python@pearwood.info> wrote:
>> One thing he missed is that there are untyped languages where
>> everything is the same type. If everything is the same type, that's
>> equivalent to there being no types at all. Examples include TCL and
>> Hypertalk, where everything are strings, and Forth, where everything
>> are two-byte words.
>>
>> But I digress. Apart from those couple of little criticisms, I think it
>> is a very useful article to read.
> 
> Continuing the digression slightly: If everything's a string, how do you
> handle aggregate types like arrays? Are they outside the type system
> altogether (like in C, where an array-of-int isn't something you can
> pass around, though pointer-to-int is)? 

I don't know about TCL, but in Hypertalk, when I said everything is a 
string, I meant it. If you want a list of strings, you create one big 
string using some delimiter (usually spaces, commas or newlines). So I 
might say something like:

# it's been a few years, I may have some of the syntax wrong
put field "list of stuff" into text
for i = 1 to the number of lines of text:
    get line i of text
    if word 3 of item 6 of it is "stop" then do_stop()
    else do_start(word 1 of item 2 of it)

Hypertalk uses (almost) natural language chunking: lines are chunks of 
text separated by newlines, items are separated by commas, and words are 
separated by spaces. So you can easily implement up to three dimensional 
arrays:

a b,c d,e f
g h,i j,k l
m n,o p,q r

is a list of three lines, each line having three items, each item having 
two words. (Oh, and there's one more layer of chunking: the character or 
char. Guess what that does?)


Actually, perhaps it's not quite true that everything is a string. 
Hypertalk also has fields, which are text fields in the GUI environment. 
Fields have properties such as the textsize and the font, as well as 
contents, which are strings. There are also buttons, which don't have 
contents, although some of them can have state like On or Off. There are 
cards, which contain fields and buttons, and backgrounds, which contain 
cards, and stacks, which contain backgrounds. So it actually was rather 
object-oriented in a way, but the objects were completely tied to the GUI 
environment. You couldn't directly create an abstract field object, 
instead you treated it like a macro playback and did things like this:

choose menu item "New Field" from "Tools" menu
set the name of field "New Field" to "foo"
set the rect of field "foo" to 25,25,100,200

or if you were really keen, or perhaps foolish:

select field tool
drag from 25,25 to 100,200
set the name of field (the number of fields) to "foo"


Despite its flaws, it was great fun to program in, and the best 
integrated GUI programming environment I've every seen by far.



-- 
Steven

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#57032

On Fri, Oct 18, 2013 at 3:45 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> I don't know about TCL, but in Hypertalk, when I said everything is a
> string, I meant it. If you want a list of strings, you create one big
> string using some delimiter (usually spaces, commas or newlines).

Fair enough. As a system, that works reasonably cleanly... if a little
inefficiently, since you need to delimit everything. But hey, your
arrays are first-class objects by definition, and that's a good thing!

ChrisA

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#57089

On Wed, 16 Oct 2013 23:49:02 -0700, Peter Cacioppi wrote:

> I don't know if I want to step into the flames here, 

Go on, be bold! You learn a lot by making bold claims and having them 
shot down. Or at least, I did. Now I know everything, so I can afford to 
be humble.

*wink*


> but my
> understanding has always been that in the absence of polymorphism the
> best you can do is "object based" programming instead of "object
> oriented" programming.

Well, that surely depends on the semantics of what you mean by "object 
based" versus "object oriented", and I don't think there is any one hard, 
universally agreed upon definition of those.


> Object based programming is a powerful step forward. The insight that by
> associating data structures and methods together you can significantly
> improve readability and robustness.

This implies that "object-based" simply means that you have *syntax* for 
associating methods with data, i.e. objects. I don't think I would agree 
with that definition. For instance, I often describe Python as "object-
based" in the sense that *all* values in Python are objects, even things 
which would be low-level primitives in some other languages, although you 
can still write procedural, imperative or functional-style code.


> Object oriented programming takes things further, most significantly by
> introducing the idea that the object reference you are referencing might
> be a run time dependent sub-class. 

And I *strongly* disagree with this. I wonder whether you have read this?

http://en.wikipedia.org/wiki/Object-oriented_programming#Fundamental_features_and_concepts

Quote:

    Benjamin C. Pierce and some other researchers view any attempt
    to distill OOP to a minimal set of features as futile. He 
    nonetheless identifies fundamental features that support the
    OOP programming style in most object-oriented languages: 
    [list of five feature]

    Similarly, in his 2003 book, Concepts in programming languages,
    John C. Mitchell identifies four main features: [...] Michael
    Lee Scott in Programming Language Pragmatics considers only
    [three features]


It is notable that polymorphism is *not* one of the three features listed 
by Scott (although it is included by the other two). So I don't agree 
that subtype polymorphism is necessary for OOP.

I can easily conceive of object-oriented languages with inheritance but
no subtype polymorphism. For instance, prototype-based OOP languages have
inheritance, but since they don't really have types in the class-based 
OOP sense, they don't have subtypes, hence no subtype polymorphism.



> Even Python, which isn't strongly typed, 

That's not the case, although that's been discussed in other posts.

> manages polymorphism by allowing the self argument to a sub-class
> of the method class.

I must admit I don't really understand what this sentence is supposed to 
mean.


> There are many wonderful examples of object based programming in C. I
> believe VB (not VB.net, the older VBA language) is object based but not
> object oriented.
> 
> True object oriented programming 

http://en.wikipedia.org/wiki/True_Scotsman_fallacy


> seems to require proper support from
> the language itself, because the run-time resolution of the "this/self"
> reference needs specific constructs in the language.

Again, I don't understand what you are trying to say here. Provided that 
the "this/self" reference has a type, what more does the language need to 
provide? The reference itself is enough to identify the instance (since 
it is the instance!) and the instance's type is enough to identify the 
type (since it is the type!).


> Bear in mind that my usual disclaimer when wading into the flames like
> this is to quote Randy Newman ... "I may be wrong .... but I don't think
> so!!"

:-)


-- 
Steven

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#57090

On Sat, Oct 19, 2013 at 8:57 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> On Wed, 16 Oct 2013 23:49:02 -0700, Peter Cacioppi wrote:
>
>> I don't know if I want to step into the flames here,
>
> Go on, be bold! You learn a lot by making bold claims and having them
> shot down.

Yes, it's a very effective technique. I just learned another meaning
of the word "trepan" via Savoynet that way. (It's a synonym for its
anagram "entrap", as well as being a surgical operation on the skull.
So now you know, too!)

>> Even Python, which isn't strongly typed,
>> manages polymorphism by allowing the self argument to a sub-class
>> of the method class.
>
> I must admit I don't really understand what this sentence is supposed to
> mean.

As I understand it, there's a little word missing: "... allowing the
self argument to BE a subclass...". That is, in this example:

class A:
    def foo(self):
        return "spam"
class B(A):
    pass

x=B()
print(x.foo())

the method named foo and defined in class A might not get, as its
'self' argument, an instance of class A, but might instead get a
subclass thereof. Thus, polymorphism. Similarly, this C example cheats
a bit, but does work:

struct A
{
    /* ... declare members here */
}
struct B
{
    struct A base;
    /* ... more members */
}

int foo(struct A *self)
{
    /* ... */
}

int main()
{
    struct B obj;
    foo((struct A *)&obj);
}

It depends on the compiler not tinkering with the layout of the
structure at all, which I don't believe is guaranteed but is fairly
safe to assume. (The equivalent C++ code could use real inheritance,
and then it is guaranteed, plus the pointer can be cast implicitly.
But we already know C++ does object oriented code more cleanly.) As
far as foo() is concerned, it's been given a 'struct A', albeit one
with a few extra members after it.

>> True object oriented programming
>> seems to require proper support from
>> the language itself, because the run-time resolution of the "this/self"
>> reference needs specific constructs in the language.
>
> Again, I don't understand what you are trying to say here. Provided that
> the "this/self" reference has a type, what more does the language need to
> provide? The reference itself is enough to identify the instance (since
> it is the instance!) and the instance's type is enough to identify the
> type (since it is the type!).

See above C example - except that true support would include implicit
upcasting, and would thus disallow cross-casting (which the C example
above would have problems with - you could cast any pointer to any
type with the exact same syntax and no compiler warning or error).

ChrisA

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#56942

> What you've said here is that "without polymorphism, you can't have
> polymorphism". :) 

Respectfully, no. I refer to the distinction between object based and object oriented programming. Wikipedia's entry is consistent with my understanding (not to argue by wiki-authority, but the terminology here isn't my personal invention).

Your example of "polymorphism in a non OO" language makes my tired head hurt. Do you have a clean little example of polymorphism being mocked in a reasonable way with pure C? There are many nice object-based C projects floating around, but real polymorphism? I think you can't do it without some bizarre work-arounds, but I'd be happy to be shown otherwise.

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#56943

Am 17.10.13 09:23, schrieb Peter Cacioppi:
> Do you have a clean little example of polymorphism being
> mocked in a reasonable way with pure C? There are many nice
> object-based C projects floating around, but real polymorphism? I
> think you can't do it without some bizarre work-arounds, but I'd be
> happy to be shown otherwise.

http://stackoverflow.com/questions/524033/how-can-i-simulate-oo-style-polymorphism-in-c/524076#524076

(Haven't tried to compile it, but I think there is an error in answer 
#5, the this pointer must be cast to VTable* before calling).

C is reasonably close to OO thanks to its structs. Most language 
constructs of C++ can be directly converted into C with just some more 
typing effort. You will have problems with exceptions (setjump?), 
templates (macros?) and RTTI.

	Christian

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#56945

On Thu, Oct 17, 2013 at 6:23 PM, Peter Cacioppi
<peter.cacioppi@gmail.com> wrote:
> Respectfully, no. I refer to the distinction between object based and object oriented programming. Wikipedia's entry is consistent with my understanding (not to argue by wiki-authority, but the terminology here isn't my personal invention).

Yep, but your definition of object oriented programming is
fundamentally based on support for polymorphism, and your opening
statement said that it's impossible without polymorphism :)

Anyway, what I sought to prove was that polymorphic object oriented
code can be written in C or any other language.

ChrisA

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#57012

On Thu, 17 Oct 2013 19:24:58 +1100, Chris Angelico wrote:

> Anyway, what I sought to prove was that polymorphic object oriented code
> can be written in C or any other language.

The proof of this is that any Turing-complete language can simulate any 
other language. Obviously the *difficulty* can vary, but any sufficiently 
expressive language can be used to write an interpreter for some other 
language which gives you the results you want.

I'm not just talking hypothetically here. Python is polymorphic, and 
there are at least two Python implementations written in C (CPython and 
Stackless). So if you took all the C code which implements object-
oriented behaviour within CPython, added it to your C project, and then 
used it directly as a framework, you would have polymorphic code written 
using nothing but C.

Of course, this wouldn't be idiomatic C code, and you won't have syntax 
for what you want, but that's why other languages get invented in the 
first place.


-- 
Steven

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#56971

Peter Cacioppi <peter.cacioppi@gmail.com> writes:

>> What you've said here is that "without polymorphism, you can't have
>> polymorphism". :) 
>
> Respectfully, no. I refer to the distinction between object based and object oriented programming. Wikipedia's entry is consistent with my understanding (not to argue by wiki-authority, but the terminology here isn't my personal invention).
>
> Your example of "polymorphism in a non OO" language makes my tired head hurt. Do you have a clean little example of polymorphism being mocked in a reasonable way with pure C? There are many nice object-based C projects floating around, but real polymorphism? I think you can't do it without some bizarre work-arounds, but I'd be happy to be shown otherwise.

The first C++ compilers were just preprocessors that translated into pure C code, which was then compiled with a C compiler. The resulting intermediate C code would be an object-oriented program in C. IIRC, the C code was reasonably clear, not really convoluted, so you would have been able to write it yourself.
-- 
Piet van Oostrum <piet@vanoostrum.org>
WWW: http://pietvanoostrum.com/
PGP key: [8DAE142BE17999C4]

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#56981

> The first C++ compilers were just preprocessors that translated into 
> pure C code ...

I agree with this.

> the C code was reasonably clear, not really convoluted, so you would have 
> been able to write it yourself. 

I disagree with this. My sense of C is that IF you are relying on preprocessors to do sophisticated things, THEN you are not writing clear C code. The implementations I've seen of polymorphism-of-structs in C are quite ugly to my eyes, and make me grateful C++ was invented.

OTOH, I've seen object-based C development projects (I.e. where you could tell what function was being called at compile time) that are quite readable. It requires coding discipline (as does readability in any language).

We might just be arguing over the definition of "readable" here. I have been told that my standards of readable are unreasonable, so perhaps I'm in the wrong here. That said, I'm just glad true OO languages exist, especially Python.

All hail Guido.

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#57004

In article <cb5c412c-7d41-4778-acc6-c822008482d7@googlegroups.com>,
 Peter Cacioppi <peter.cacioppi@gmail.com> wrote:

> OTOH, I've seen object-based C development projects (I.e. where you could 
> tell what function was being called at compile time) that are quite readable. 

If you can tell what function will be called by looking at the code, 
it's not object oriented enough :-)

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#57005

On Fri, Oct 18, 2013 at 11:01 AM, Roy Smith <roy@panix.com> wrote:
> In article <cb5c412c-7d41-4778-acc6-c822008482d7@googlegroups.com>,
>  Peter Cacioppi <peter.cacioppi@gmail.com> wrote:
>
>> OTOH, I've seen object-based C development projects (I.e. where you could
>> tell what function was being called at compile time) that are quite readable.
>
> If you can tell what function will be called by looking at the code,
> it's not object oriented enough :-)

Is that why there's the International Object-oriented C Code Contest
at www.ioccc.org ?

ChrisA

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