Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #25473 > unrolled thread

Encapsulation, inheritance and polymorphism

Back to article view | Back to comp.lang.python

Contents

  Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 09:45 +0100
    Re: Encapsulation, inheritance and polymorphism Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-07-17 06:03 -0400
      Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 12:24 +0100
        Re: Encapsulation, inheritance and polymorphism Larry Hudson <orgnut@yahoo.com> - 2012-07-18 00:10 -0700
    Re: Encapsulation, inheritance and polymorphism Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-07-17 11:30 +0200
      Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 12:01 +0100
        Re: Encapsulation, inheritance and polymorphism Dave Angel <d@davea.name> - 2012-07-17 07:23 -0400
        Re: Encapsulation, inheritance and polymorphism Andrew Berg <bahamutzero8825@gmail.com> - 2012-07-17 06:37 -0500
          Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 12:44 +0100
            Re: Encapsulation, inheritance and polymorphism Andrew Berg <bahamutzero8825@gmail.com> - 2012-07-17 06:53 -0500
            Re: Encapsulation, inheritance and polymorphism Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-17 14:35 +0100
          Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 15:01 +0100
            Re: Encapsulation, inheritance and polymorphism Andrew Berg <bahamutzero8825@gmail.com> - 2012-07-17 09:16 -0500
              Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 15:26 +0100
            Re: Encapsulation, inheritance and polymorphism Terry Reedy <tjreedy@udel.edu> - 2012-07-17 13:30 -0400
            Re: Encapsulation, inheritance and polymorphism Andrew Berg <bahamutzero8825@gmail.com> - 2012-07-17 12:57 -0500
        Re: Encapsulation, inheritance and polymorphism Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-07-17 14:18 +0200
        Re: Encapsulation, inheritance and polymorphism Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-17 14:29 +0100
        Re: Encapsulation, inheritance and polymorphism Roy Smith <roy@panix.com> - 2012-07-17 09:52 -0400
          Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 15:23 +0100
            Re: Encapsulation, inheritance and polymorphism Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-17 17:26 +0100
              Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 17:46 +0100
            Re: Encapsulation, inheritance and polymorphism Terry Reedy <tjreedy@udel.edu> - 2012-07-17 13:07 -0400
              Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 20:29 +0100
                Re: Encapsulation, inheritance and polymorphism Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-17 20:39 +0100
                  Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 20:52 +0100
                  Re: Encapsulation, inheritance and polymorphism John Ladasky <john_ladasky@sbcglobal.net> - 2012-08-18 23:05 -0700
                  Re: Encapsulation, inheritance and polymorphism John Ladasky <john_ladasky@sbcglobal.net> - 2012-08-18 23:05 -0700
                Re: Encapsulation, inheritance and polymorphism Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-17 18:57 -0400
            Re: Encapsulation, inheritance and polymorphism Ethan Furman <ethan@stoneleaf.us> - 2012-07-17 10:29 -0700
            Re: Encapsulation, inheritance and polymorphism Chris Angelico <rosuav@gmail.com> - 2012-07-18 04:01 +1000
            Re: Encapsulation, inheritance and polymorphism Tim Chase <python.list@tim.thechases.com> - 2012-07-17 12:51 -0500
            Re: Encapsulation, inheritance and polymorphism Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-17 19:18 +0100
              Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 19:36 +0100
                Re: Encapsulation, inheritance and polymorphism Andrew Cooper <amc96@cam.ac.uk> - 2012-07-18 01:46 +0100
                  Re: Encapsulation, inheritance and polymorphism rusi <rustompmody@gmail.com> - 2012-07-17 20:54 -0700
                  Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-18 10:06 +0100
                    Re: Encapsulation, inheritance and polymorphism Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2012-07-18 14:01 +0200
                    Re: Encapsulation, inheritance and polymorphism "BartC" <bc@freeuk.com> - 2012-07-19 01:41 +0100
                  Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-18 13:05 +0000
                    Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-18 15:40 +0100
                      Re: Encapsulation, inheritance and polymorphism Chris Angelico <rosuav@gmail.com> - 2012-07-19 01:04 +1000
                        Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-19 01:22 +0000
                          Re: Encapsulation, inheritance and polymorphism Chris Angelico <rosuav@gmail.com> - 2012-07-19 15:09 +1000
                      Re: Encapsulation, inheritance and polymorphism Ethan Furman <ethan@stoneleaf.us> - 2012-07-18 08:32 -0700
                        Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-18 16:49 +0100
                      Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-19 01:34 +0000
                        Re: Encapsulation, inheritance and polymorphism rusi <rustompmody@gmail.com> - 2012-07-18 23:09 -0700
                          Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-19 09:56 +0100
                            Re: Encapsulation, inheritance and polymorphism rusi <rustompmody@gmail.com> - 2012-07-19 08:58 -0700
                          Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-19 12:59 +0000
                            Re: Encapsulation, inheritance and polymorphism Roy Smith <roy@panix.com> - 2012-07-19 09:06 -0400
                              Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-20 07:24 +0000
                                Re: Encapsulation, inheritance and polymorphism rusi <rustompmody@gmail.com> - 2012-07-20 01:21 -0700
                            Re: Encapsulation, inheritance and polymorphism Paul Rudin <paul.nospam@rudin.co.uk> - 2012-07-19 18:22 +0100
                            Re: Encapsulation, inheritance and polymorphism Tim Chase <python.list@tim.thechases.com> - 2012-07-19 13:20 -0500
                            Re: Encapsulation, inheritance and polymorphism Chris Angelico <rosuav@gmail.com> - 2012-07-20 04:28 +1000
                            Re: Encapsulation, inheritance and polymorphism Tim Chase <python.list@tim.thechases.com> - 2012-07-19 13:50 -0500
                              Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-20 08:11 +0000
                                Re: Encapsulation, inheritance and polymorphism Erik Max Francis <max@alcyone.com> - 2012-07-20 02:08 -0700
                                  Re: Encapsulation, inheritance and polymorphism "BartC" <bc@freeuk.com> - 2012-07-20 11:28 +0100
                                    Re: Encapsulation, inheritance and polymorphism Erik Max Francis <max@alcyone.com> - 2012-07-21 14:32 -0700
                                      Re: Encapsulation, inheritance and polymorphism Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-23 16:36 +0000
                            Re: Encapsulation, inheritance and polymorphism Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-19 16:47 -0400
                              Re: Encapsulation, inheritance and polymorphism John Gordon <gordon@panix.com> - 2012-07-19 21:01 +0000
                                Re: Encapsulation, inheritance and polymorphism Chris Angelico <rosuav@gmail.com> - 2012-07-20 08:20 +1000
                                  Re: Encapsulation, inheritance and polymorphism John Gordon <gordon@panix.com> - 2012-07-19 22:23 +0000
                                  Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-20 08:27 +0000
                                    Re: Encapsulation, inheritance and polymorphism Virgil Stokes <vs@it.uu.se> - 2012-07-20 11:05 +0200
                                      Re: Encapsulation, inheritance and polymorphism Hans Mulder <hansmu@xs4all.nl> - 2012-07-20 19:45 +0200
                                      Re: Encapsulation, inheritance and polymorphism Erik Max Francis <max@alcyone.com> - 2012-07-21 14:28 -0700
                                    Re: Encapsulation, inheritance and polymorphism Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-20 13:57 -0400
                                Re: Encapsulation, inheritance and polymorphism Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-19 15:13 -0600
                                Re: Encapsulation, inheritance and polymorphism Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-07-19 17:30 -0400
                                Re: Encapsulation, inheritance and polymorphism Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-20 10:00 +0100
                      Re: Encapsulation, inheritance and polymorphism Terry Reedy <tjreedy@udel.edu> - 2012-07-19 02:11 -0400
                    Re: Encapsulation, inheritance and polymorphism Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-23 16:18 +0000
                      Re: Encapsulation, inheritance and polymorphism Chris Angelico <rosuav@gmail.com> - 2012-07-24 02:15 +1000
                      Re: Encapsulation, inheritance and polymorphism Robert Miles <robertmiles@teranews.com> - 2012-08-19 00:21 -0500
                        Re: Encapsulation, inheritance and polymorphism Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-19 09:55 +0100
                          Re: Encapsulation, inheritance and polymorphism lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-19 12:50 +0100
                            Re: Encapsulation, inheritance and polymorphism Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-19 13:06 +0100
            Re: Encapsulation, inheritance and polymorphism Ethan Furman <ethan@stoneleaf.us> - 2012-07-17 11:43 -0700
            Re: Encapsulation, inheritance and polymorphism Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-07-17 15:05 -0400
            Re: Encapsulation, inheritance and polymorphism Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-17 20:33 +0100
            Re: Encapsulation, inheritance and polymorphism Ian <hobson42@gmail.com> - 2012-07-17 19:59 +0100
          Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-18 12:58 +0000
            Re: Encapsulation, inheritance and polymorphism Roy Smith <roy@panix.com> - 2012-07-18 09:07 -0400
              Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-18 14:31 +0000
            Re: Encapsulation, inheritance and polymorphism Dave Angel <d@davea.name> - 2012-07-18 12:33 -0400
              Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-19 01:23 +0000
        Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-18 12:43 +0000
        Re: Encapsulation, inheritance and polymorphism Grant Edwards <invalid@invalid.invalid> - 2012-07-18 14:34 +0000
          Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-18 15:48 +0100
            Re: Encapsulation, inheritance and polymorphism Chris Angelico <rosuav@gmail.com> - 2012-07-19 01:09 +1000
              Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-18 16:36 +0100
            Re: Encapsulation, inheritance and polymorphism Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-19 01:14 +0000
              Re: Encapsulation, inheritance and polymorphism MRAB <python@mrabarnett.plus.com> - 2012-07-19 02:28 +0100
                Re: Encapsulation, inheritance and polymorphism "OKB (not okblacke)" <brenNOSPAMbarn@NObrenSPAMbarn.net> - 2012-07-19 16:52 +0000
          Re: Encapsulation, inheritance and polymorphism Andrew Berg <bahamutzero8825@gmail.com> - 2012-07-18 10:00 -0500
    Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 13:01 +0100
      Re: Encapsulation, inheritance and polymorphism Terry Reedy <tjreedy@udel.edu> - 2012-07-17 13:24 -0400
        Re: Encapsulation, inheritance and polymorphism Lipska the Kat <lipska@lipskathekat.com> - 2012-07-17 19:21 +0100
      Re: Encapsulation, inheritance and polymorphism MRAB <python@mrabarnett.plus.com> - 2012-07-17 18:43 +0100
      Re: Encapsulation, inheritance and polymorphism Tim Chase <python.list@tim.thechases.com> - 2012-07-17 12:56 -0500
      Re: Encapsulation, inheritance and polymorphism Arnaud Delobelle <arnodel@gmail.com> - 2012-07-18 11:35 +0100

Page 1 of 6  [1] 2 3 4 5 6  Next page →

#25473 — Encapsulation, inheritance and polymorphism

Pythoners

Python 2.7.3
Ubuntu Linux 12.04 LTS

I've been taking a brief look at Python.

 From the tutorial documentation I get the following

'Python is an easy to learn, powerful programming language. It has 
efficient high-level data structures and a simple but effective approach 
to object-oriented programming'.

I was expecting (hoping) to see in depth documentation relating to Class 
construction, extension mechanisms and runtime polymorphism.

What I actually get is a confusion of Classes, modules, scripts and 
whatever else.

Is Python truly OO or is it just one way to use the language. I see some 
documentation relating to classes but nothing on instantiation .. in 
fact the documentation appears to say that classes are used in a static 
way e.g ClassName.method(), and command line scripting is really outside 
the scope of other OO languages I have experienced.

Is there a previous discussion in the group that I could read.

Many thanks

Lipska

-- 
Lipska the Kat: Troll hunter, Sandbox destroyer
and Farscape dreamer.

[toc] | [next] | [standalone]

#25481

On Tue, Jul 17, 2012 at 4:45 AM, Lipska the Kat <lipska@lipskathekat.com> wrote:
> Is Python truly OO or is it just one way to use the language. I see some
> documentation relating to classes but nothing on instantiation .. in fact
> the documentation appears to say that classes are used in a static way e.g
> ClassName.method(), and command line scripting is really outside the scope
> of other OO languages I have experienced.

It doesn't look like you're reading the section on classes:

http://docs.python.org/tutorial/classes.html

You create a class like this:

    class MyClass(MySuperclass1, MySuperclass2):
        # class attributes and methods
        attr = 3
        def method(self): print self.attr

You can instantiate it by calling the class, as if it were a function:

    myinstance = MyClass()

You call a method getting the method (myinstance.method), and then
calling that as if it were a function.

    myinstance.method()

Polymorphism is "duck typed" -- that is, it's based on the
presence/absence of attributes and methods, not on declared interfaces
(Python has no interfaces). So, for example, "foo.read()" works on any
object bound to the name "foo", as long as it has a read method that
takes no parameters. This could be a file-like object, but it could
also be something completely different that just happens to have a
method by the same name.

> Is there a previous discussion in the group that I could read.

Man, I dunno, the list archives are impossible to navigate.

-- Devin

[toc] | [prev] | [next] | [standalone]

#25487

On 17/07/12 11:03, Devin Jeanpierre wrote:
> On Tue, Jul 17, 2012 at 4:45 AM, Lipska the Kat<lipska@lipskathekat.com>  wrote:
>> Is Python truly OO or is it just one way to use the language. I see some
>> documentation relating to classes but nothing on instantiation .. in fact
>> the documentation appears to say that classes are used in a static way e.g
>> ClassName.method(), and command line scripting is really outside the scope
>> of other OO languages I have experienced.
>
> It doesn't look like you're reading the section on classes:
>
> http://docs.python.org/tutorial/classes.html

Thanks, I wasn't, there is too much to do and not enough time to do it.
So now I just need to chill out a bit and get into 'documentation 
reading mode' again


> Polymorphism is "duck typed" --

Yes, I've been reading the wikipedia entry on this ... this type of 
polymorphism is not familiar to me ... I come from a Java background. 
more reading I guess.

snip

> -- Devin

Thanks for your time and I'll try to do a bit better with the reading 
thing before asking more questions... not sure about this obsession with 
code indentation though :-|


-- 
Lipska the Kat: Troll hunter, Sandbox destroyer
and Farscape dreamer of Aeryn Sun.

[toc] | [prev] | [next] | [standalone]

#25559

On 07/17/2012 04:24 AM, Lipska the Kat wrote:
...
> Thanks for your time and I'll try to do a bit better with the reading thing before asking more
> questions... not sure about this obsession with code indentation though :-|
>

I think it's inaccurate to call this indentation an obsession, it's part of Python's defined 
syntax.  It's used INSTEAD OF punctuation or keywords (like {} or BEGIN END).  If you're already 
used to indenting your code consistently, you'll be surprised at how quickly it becomes a 
non-issue when you start using Python.

It's a bit dated, but you might find http://www.linuxjournal.com/article/3882 to be an 
interesting read.

      -=- Larry -=-

[toc] | [prev] | [next] | [standalone]

#25483

Welcome!

Am 17.07.2012 10:45, schrieb Lipska the Kat:
> I was expecting (hoping) to see in depth documentation relating to Class
> construction, extension mechanisms and runtime polymorphism.

In addition to this forum for direct help and discussion, two 
suggestions: Firstly, it could help if you mentioned what programming 
languages you are fluent in, in order to help traditional misconceptions 
and to draw parallels. Secondly, http://docs.python.org is the central 
hub to tutorials and documentation.


> What I actually get is a confusion of Classes, modules, scripts and
> whatever else.

Due to the very dynamic nature of Python, types (classes), modules and 
functions are themselves objects that can be manipulated.


> Is Python truly OO or is it just one way to use the language.

Python supports OOP, but it doesn't enforce it. You can use other 
paradigms, too.


> I see some documentation relating to classes but nothing on
> instantiation .. in fact the documentation appears to say that classes
 > are used in a static way e.g ClassName.method(), and command line
 > scripting is really outside the scope of other OO languages I have
 > experienced.

I think you are confused. For the documentation, it would help to know 
which documentation exactly seems to make such claims. For the thing 
about commandline scripting, I'm afraid you will have to adjust your 
expectations.

BTW: In general, you instantiate a class by just calling the class' name 
like a function. If e.g. ClassName is a class, ClassName() instantiates 
this class.


Good luck!

Uli

[toc] | [prev] | [next] | [standalone]

#25484

On 17/07/12 10:30, Ulrich Eckhardt wrote:
> Welcome!
>
> Am 17.07.2012 10:45, schrieb Lipska the Kat:
>> I was expecting (hoping) to see in depth documentation relating to Class
>> construction, extension mechanisms and runtime polymorphism.
>
> In addition to this forum for direct help and discussion, two
> suggestions: Firstly, it could help if you mentioned what programming
> languages you are fluent in

For the past 9 years I have been developing in Java, everything from 
device drivers (well firmware interfaces would be a better description)
to serverside business logic implemented using POJOs and database 
interfaces along with some in depth work with earlier versions of J2EE 
including EJBs and of course the obligatory frameworks. There's more but 
you get the idea.

My speciality if you like is the design of high availability real time 
business systems right from high level natural language specifications 
to detailed use cases and associated models in UML. I also do some 
implementation work although not so much these days. phew! my resume in 
a nutshell I suppose

Earlier on in my career I did some fairly low level stuff in C and C++ 
although the mists of time and all that ...

Anyway, I'm looking at Python as a rapid prototyping language.
I have an idea and just want to get it down in basic outline code as 
quickly as possible before it departs my aging brain... I'm not used to 
using variables without declaring their type ... (well I used to do 
Visual Basic many years ago) It just seems so weird, and what's this 
obsession with 'correct' indentation of code ???

>in order to help traditional misconceptions
> and to draw parallels. Secondly, http://docs.python.org is the central
> hub to tutorials and documentation.
>
>
>> What I actually get is a confusion of Classes, modules, scripts and
>> whatever else.
>
> Due to the very dynamic nature of Python, types (classes), modules and
> functions are themselves objects that can be manipulated.
>
>

snip

>
>> I see some documentation relating to classes but nothing on
>> instantiation .. in fact the documentation appears to say that classes
>  > are used in a static way e.g ClassName.method(), and command line
>  > scripting is really outside the scope of other OO languages I have
>  > experienced.
>
> I think you are confused.

Highly likely

> For the documentation, it would help to know
> which documentation exactly seems to make such claims. For the thing
> about commandline scripting, I'm afraid you will have to adjust your
> expectations.

I'll try to find it again

>
> BTW: In general, you instantiate a class by just calling the class' name
> like a function. If e.g. ClassName is a class, ClassName() instantiates
> this class.
>
>
> Good luck!

Thank you, and thank you for your kind response

Lipska


-- 
Lipska the Kat: Troll hunter, Sandbox destroyer
and Farscape dreamer of Aeryn Sun.

[toc] | [prev] | [next] | [standalone]

#25486

On 07/17/2012 07:01 AM, Lipska the Kat wrote:
> <SNIP>
>
> Anyway, I'm looking at Python as a rapid prototyping language.
> I have an idea and just want to get it down in basic outline code as
> quickly as possible before it departs my aging brain... I'm not used
> to using variables without declaring their type ... (well I used to do
> Visual Basic many years ago) It just seems so weird, and what's this
> obsession with 'correct' indentation of code ???
>

Welcome to comp.lang.python.  I hope you enjoy learning and using Python.

Indentation isn't just custom in Python.  It's part of the syntax. 
Other languages use braces, or keywords, to indicate scope, but Python
uses indentation.  Other than the occasional tab to confuse things, the
rules are pretty simple.

You must indent the body of a function, the scope of an if or else
clause, or other similar language pieces (class, try, except, ...)
Within such a scope, you cannot change indentation, except of course for
a nested scope.
At the end of such scope you must outdent to the previous state.

The convention is to use 4 spaces per indentation, but the language will
accept any amount, as long as it's consistent within any single scope. 
And although mixing tabs and space worked in Python 2.x, sort of, it's
disallowed in Python 3.

An expression may span multiple lines, but only if it's unambiguous to
the compiler (eg. a pending left paren with no matching right paren
yet).  In that case. indentation of the subsequent lines is unrestricted.

HTH

-- 

DaveA

[toc] | [prev] | [next] | [standalone]

#25488

On 7/17/2012 6:01 AM, Lipska the Kat wrote:
> Anyway, I'm looking at Python as a rapid prototyping language.
> I have an idea and just want to get it down in basic outline code as 
> quickly as possible before it departs my aging brain... I'm not used to 
> using variables without declaring their type ... (well I used to do 
> Visual Basic many years ago) It just seems so weird, and what's this 
> obsession with 'correct' indentation of code ???
"Pythonic" is (or at least should be) a word you encounter frequently in
discussions of Python code. Learn what is considered Pythonic and then
write Python code that way if you want to work with the language rather
than fight it. Duck-typing is very Pythonic and so is readable code. As
Dave mentioned, indentation is part of the syntax - blocks must be
indented with either tabs or spaces (choose one - if you mix them
ambiguously, an IndentationError will be raised). Try "from __future__
import braces" and "import this" for some insight. ;)

The official tutorial gives a great overview of the language and has
links to reference material that goes into greater detail:
http://docs.python.org/tutorial/ (Python 2.7)
http://docs.python.org/py3k/tutorial/ (Python 3.2)

On a side note, I would highly recommend learning Python 3 (3.2 is the
latest stable version) unless you have an explicit need for Python 2
(some major 3rd-party libraries have not been ported yet). Python 2
won't get any new features; it will simply get bug fixes until its EOL
in 2014 (15?).
-- 
CPython 3.3.0b1 | Windows NT 6.1.7601.17803

[toc] | [prev] | [next] | [standalone]

#25489

On 17/07/12 12:37, Andrew Berg wrote:
> On 7/17/2012 6:01 AM, Lipska the Kat wrote:
>> Anyway, I'm looking at Python as a rapid prototyping language.

snip

> "Pythonic" is (or at least should be) a word you encounter frequently in
> discussions of Python code. Learn what is considered Pythonic and then
> write Python code that way if you want to work with the language rather
> than fight it. Duck-typing is very Pythonic

You're not kidding, the 'duck' example at 
http://en.wikipedia.org/wiki/Duck_typing made me check I hadn't overdone 
the medication this morning. That is just plain ...weird. It will take 
me a while to form non knee jerk opinions of this for sure.

snip

> On a side note, I would highly recommend learning Python 3 (3.2 is the
> latest stable version) unless you have an explicit need for Python 2
> (some major 3rd-party libraries have not been ported yet). Python 2
> won't get any new features; it will simply get bug fixes until its EOL
> in 2014 (15?).

I'll check it out, thanks.

Lipska


-- 
Lipska the Kat: Troll hunter, Sandbox destroyer
and Farscape dreamer of Aeryn Sun.

[toc] | [prev] | [next] | [standalone]

#25490

On 7/17/2012 6:44 AM, Lipska the Kat wrote:
> I'll check it out, thanks.
I forgot to add this:
http://wiki.python.org/moin/Python2orPython3

It's a little outdated (there is more progress toward py3k by 3rd-party
libraries every day), but still quite helpful.
-- 
CPython 3.3.0b1 | Windows NT 6.1.7601.17803

[toc] | [prev] | [next] | [standalone]

#25498

On 17/07/2012 12:44, Lipska the Kat wrote:
>
> You're not kidding, the 'duck' example at
> http://en.wikipedia.org/wiki/Duck_typing made me check I hadn't overdone
> the medication this morning. That is just plain ...weird. It will take
> me a while to form non knee jerk opinions of this for sure.
>
> Lipska
>
>

It's difficult to get junkies off of their addictive substances but I'm 
sure that the qualities of Python will eventually overcome your Java 
habit :)

-- 
Cheers.

Mark Lawrence.

[toc] | [prev] | [next] | [standalone]

#25502

On 17/07/12 12:37, Andrew Berg wrote:
> On 7/17/2012 6:01 AM, Lipska the Kat wrote:

snip

> On a side note, I would highly recommend learning Python 3 (3.2 is the
> latest stable version) unless you have an explicit need for Python 2
> (some major 3rd-party libraries have not been ported yet). Python 2
> won't get any new features; it will simply get bug fixes until its EOL
> in 2014 (15?).

Wow, that was a blast from the past
Just downloaded, unzipped, untarred, configured, made and installed 
python 3.2.3 ... it's YEARS since I've done this, makes me feel young again.

Lispka


-- 
Lipska the Kat: Troll hunter, Sandbox destroyer
and Farscape dreamer of Aeryn Sun.

[toc] | [prev] | [next] | [standalone]

#25504

On 7/17/2012 9:01 AM, Lipska the Kat wrote:
> Wow, that was a blast from the past
> Just downloaded, unzipped, untarred, configured, made and installed 
> python 3.2.3 ... it's YEARS since I've done this, makes me feel young again.
Most Linux distributions should have a premade package for stable Python
versions - apt-get install python3 or something like that. Python 2 is
generally the default Python because of all the system scripts that
haven't been ported to py3k.
-- 
CPython 3.3.0b1 | Windows NT 6.1.7601.17803

[toc] | [prev] | [next] | [standalone]

#25506

On 17/07/12 15:16, Andrew Berg wrote:
> On 7/17/2012 9:01 AM, Lipska the Kat wrote:
>> Wow, that was a blast from the past
>> Just downloaded, unzipped, untarred, configured, made and installed
>> python 3.2.3 ... it's YEARS since I've done this, makes me feel young again.
> Most Linux distributions should have a premade package for stable Python
> versions - apt-get install python3 or something like that.

Not as much fun though is it :-)

Lipska

-- 
Lipska the Kat: Troll hunter, Sandbox destroyer
and Farscape dreamer of Aeryn Sun.

[toc] | [prev] | [next] | [standalone]

#25517

On 7/17/2012 10:16 AM, Andrew Berg wrote:
> On 7/17/2012 9:01 AM, Lipska the Kat wrote:
>> Wow, that was a blast from the past
>> Just downloaded, unzipped, untarred, configured, made and installed
>> python 3.2.3 ... it's YEARS since I've done this, makes me feel young again.

> Most Linux distributions should have a premade package for stable Python
> versions - apt-get install python3 or something like that.

I am just curious: how long will it take 'most Linux distributions' to 
premake the even better 3.3.0 (after it comes out) and change the 
default python3 to that? Do any of them have a premade 3.3.0b0 
available? (In some ways, it is already better than 3.2.3.)

-- 
Terry Jan Reedy

[toc] | [prev] | [next] | [standalone]

#25523

On 7/17/2012 12:30 PM, Terry Reedy wrote:
> (In some ways, it is already better than 3.2.3.)
I certainly make heavy use of some of the new features. I'm not sure we
can have enough separate exceptions for OS errors without exhausting
every possibility and I might start looking for excuses to use the lzma
module. :P

-- 
CPython 3.3.0b1 | Windows NT 6.1.7601.17803

[toc] | [prev] | [next] | [standalone]

#25496

Am 17.07.2012 13:01, schrieb Lipska the Kat:
> On 17/07/12 10:30, Ulrich Eckhardt wrote:
>> Am 17.07.2012 10:45, schrieb Lipska the Kat:
>>> I was expecting (hoping) to see in depth documentation relating to Class
>>> construction, extension mechanisms and runtime polymorphism.
>>
>> In addition to this forum for direct help and discussion, two
>> suggestions: Firstly, it could help if you mentioned what programming
>> languages you are fluent in
>
> For the past 9 years I have been developing in Java  [...]

Java is usually called an OOP language, because everything you do there 
is put into a class. Free functions don't exist, the closest you get is 
class-static functions (correct me if I'm wrong, I'm not really fluent 
in that language). In Python, you have the choice to use OOP, but you 
can also use free functions or mix those.


> I'm not used to using variables without declaring their type

As a C++ programmer (roughly 80%C++, 15%Python, 5%C) I know that 
feeling. Having types declared in advance just helps by having the 
compiler check if the passed arguments are correct. Not having this 
gives both freedom but also bears dangers.


> what's this obsession with 'correct' indentation of code ???

You'll get used to it and then start loving it.

;)

Uli

[toc] | [prev] | [next] | [standalone]

#25497

On 17/07/2012 12:01, Lipska the Kat wrote:
>
> Anyway, I'm looking at Python as a rapid prototyping language.
>
> Lipska
>

One of the huge advantages of Python here is that you can simply blast 
stuff into the interactive prompt and see what happens, no need to write 
a script.

-- 
Cheers.

Mark Lawrence.

[toc] | [prev] | [next] | [standalone]

#25500

In article <-8SdnVrXGqie25jNnZ2dnUVZ7qKdnZ2d@bt.com>,
 Lipska the Kat <lipska@lipskathekat.com> wrote:

> I'm not used to using variables without declaring their type 

If you truly wanted to recreate this type-bondage style of programming 
in Python, it's easy enough to do.

Where you would write in C++:

// Type matching will get checked at compile-time
void my_function(MassivelyParallelFrobinator& mpf, OtherThing& ot) {
   blah, blah, blah
}

you could write in Python:

# Type matching will get checked at run-time
def my_function(mpf, ot):
   assert isinstance(mpf, MassivelyParallelFrobinator)
   assert isinstance(ot, OtherThing)

but that's just not the way people write code in Python.

[toc] | [prev] | [next] | [standalone]

#25505

On 17/07/12 14:52, Roy Smith wrote:
> In article<-8SdnVrXGqie25jNnZ2dnUVZ7qKdnZ2d@bt.com>,
>   Lipska the Kat<lipska@lipskathekat.com>  wrote:
>
>> I'm not used to using variables without declaring their type
>
> If you truly wanted to recreate this type-bondage style of programming
> in Python, it's easy enough to do.

snip

Well 'type-bondage' is a strange way of thinking about compile time type 
checking and making code easier to read (and therefor debug) but
I'm not about to get into some religious war about declaring a variables 
type. I'll just say that I prefer to devote testing efforts to the real 
danger area which in my experience is 'user' input.
Clients look dimly on runtime errors however they occur and if I can 
leave it to the compiler to check as much as possible then I'll take that.

I do understand however that compiling an intepreted language doesn't 
really make sense however i'm sure there are interpreted languages that 
allow pre-execution type checking ... aren't there ? Oh yes, there's one 
called Java :-)

Still, I'm sure you're only kidding around with me :-)

Lipska

-- 
Lipska the Kat: Troll hunter, Sandbox destroyer
and Farscape dreamer of Aeryn Sun.

[toc] | [prev] | [next] | [standalone]

Page 1 of 6  [1] 2 3 4 5 6  Next page →

Back to top | Article view | comp.lang.python

csiph-web