r...@zedat.fu-berlin.de (Stefan Ram) writes:
> Julieta Shem writes:
>>r...@zedat.fu-berlin.de (Stefan Ram) writes:
>>>Later, I looked at a book in a bookstore; it was a book
>>>about programming by Barbara Liskov that came out after the
>>>LSP was already mentioned often, and as far as I could se
Greg Ewing writes:
> On 4/11/22 1:29 am, Julieta Shem wrote:
>> Perhaps I can reduce the
>> class Pair to just being a pair as we know it, made of two things, then
>> we create a class called Sequence, which is really a composition of
>> Pairs, comes with a length method and we derive Stack from
On 5/11/22 4:25 am, Chris Angelico wrote:
Maybe it's one of those terms that is useless for actual coding
(because practicality beats purity), but good for discussions?
I'm not sure it's much good for discussions, either. I don't
really care whether a language is "purely OO" or not, whatever
th
On Sat, 5 Nov 2022 at 02:18, Greg Ewing wrote:
>
> On 4/11/22 12:50 am, Chris Angelico wrote:
> > In Python, everything is an object. Doesn't that equally mean that
> > Python is purely OOP?
>
> Depends on what you mean by "purely oop". To me it suggests a
> language in which dynamically-dispatche
On Sat, 5 Nov 2022 at 02:21, Greg Ewing wrote:
>
> > r...@zedat.fu-berlin.de (Stefan Ram) writes [that Barbara Liskov said]:
> >
> >> |If for each object o1 of type S there is an object o2 of
> >> |type T such that for all programs P defined in terms of T,
> >> |the behavior of P is unchanged when
On 4/11/22 7:51 am, Julieta Shem wrote:
(The empty documentation seems to satisfy the principle.)
All the more reason to document your classes!
More seriously, there's always at least a (possibly fuzzily) implied
contract, because of the names you choose for things if nothing else.
--
Greg
-
r...@zedat.fu-berlin.de (Stefan Ram) writes [that Barbara Liskov said]:
|If for each object o1 of type S there is an object o2 of
|type T such that for all programs P defined in terms of T,
|the behavior of P is unchanged when o1 is substituted for o2
|then S is a subtype of T.
That seems over
On 4/11/22 12:50 am, Chris Angelico wrote:
In Python, everything is an object. Doesn't that equally mean that
Python is purely OOP?
Depends on what you mean by "purely oop". To me it suggests a
language in which dynamically-dispatched methods are the only
form of code. Python is not one of thos
On 4/11/22 1:29 am, Julieta Shem wrote:
Perhaps I can reduce the
class Pair to just being a pair as we know it, made of two things, then
we create a class called Sequence, which is really a composition of
Pairs, comes with a length method and we derive Stack from it.
That sounds better. But be
https://www.oreilly.com/library/view/beginning-c-30/9780470261293/9780470261293_a_short_history_of_object-oriented_progr.html
--
https://mail.python.org/mailman/listinfo/python-list
On 03/11/2022 18:29, Chris Angelico wrote:
> On Fri, 4 Nov 2022 at 05:21, Julieta Shem wrote:
>>
>> Chris Angelico writes:
>>
>>> On Thu, 3 Nov 2022 at 21:44, Alan Gauld wrote:
Also Python is not a purely OOP language, in that you can write
functional and procedural code in Python if y
r...@zedat.fu-berlin.de (Stefan Ram) writes:
> Julieta Shem writes:
>>I'll definitely look up the Liskov
>>substitution principle and try to understand it.
>
> I found the LSP to be very confusing:
>
> First, it's was hard for me to actually get a clear sou
r...@zedat.fu-berlin.de (Stefan Ram) writes:
> Julieta Shem writes:
[...]
> 2. a. 1. Remark
>
> One can observe this ease especially when one defines a new
> class with a standard verb and then standard procedures
> "magically" use this new method, as in:
>
> class MyNewClass:
> de
On Fri, 4 Nov 2022 at 05:21, Julieta Shem wrote:
>
> Chris Angelico writes:
>
> > On Thu, 3 Nov 2022 at 21:44, Alan Gauld wrote:
> >> Also Python is not a purely OOP language, in that you can write
> >> functional and procedural code in Python if you wish. In
> >> Smalltalk thats notionally impo
Chris Angelico writes:
> On Thu, 3 Nov 2022 at 21:44, Alan Gauld wrote:
>> Also Python is not a purely OOP language, in that you can write
>> functional and procedural code in Python if you wish. In
>> Smalltalk thats notionally impossible because everything
>> is an object. And all programming
Greg Ewing writes:
> On 3/11/22 1:37 pm, Julieta Shem wrote:
>> The code for computing the length of a Pair (which is really a linked
>> list) happens to be the same for computing the length of a Stack.
>
> I would question whether that should be a method of Pair at all,
> since it's not the leng
r...@zedat.fu-berlin.de (Stefan Ram) writes:
> Julieta Shem writes:
>>That's very interesting. Would you share the complete thread of e-mail?
>>I would love to read it word for word.
>
> Yes, with pleasure! A quotation from my corresponding web page:
>
> (For technical reasons, the web page
On Thu, 3 Nov 2022 at 21:44, Alan Gauld wrote:
> Also Python is not a purely OOP language, in that you can write
> functional and procedural code in Python if you wish. In
> Smalltalk thats notionally impossible because everything
> is an object. And all programming statements are messages
> to ob
From: Python-list on
behalf of Alan Gauld
Date: Thursday, November 3, 2022 at 6:45 AM
To: Julieta Shem , python-list@python.org
Subject: Re: an oop question
*** Attention: This is an external email. Use caution responding, opening
attachments or clicking on links. ***
On 03/11/2022 00:25
On 03/11/2022 00:25, Julieta Shem wrote:
>> |OOP to me means only messaging, local retention and protection and
>> |hiding of state-process, and extreme late-binding of all things.
>
> I'm wondering how Python fails to satisfy his definition.
Python doesn't do any form of data protection/hiding.
r...@zedat.fu-berlin.de (Stefan Ram) writes:
> Greg Ewing writes:
>>I don't see any overlap between these at the conceptual level.
>
> It might come from early LISP dialects. In early LISPs, the
> only basic means to combine data into a larger assembly of
> data was the dotted pair and NULL
On 3/11/22 1:37 pm, Julieta Shem wrote:
The code for computing the length of a Pair (which is really a linked
list) happens to be the same for computing the length of a Stack.
I would question whether that should be a method of Pair at all,
since it's not the length of the pair itself, but the
Alan Gauld writes:
> On 01/11/2022 17:58, Julieta Shem wrote:
[...]
>>> IS-A relationship, so Stack inheriting Pair would mean that a Stack
>>> was a Pair. That is not really true.
>>
>> That's another interesting observation. I do not have much
>> understanding of how to really think of thes
Dennis Lee Bieber writes:
> On 2 Nov 2022 09:56:28 GMT, r...@zedat.fu-berlin.de (Stefan Ram) declaimed
> the following:
>
>
>> Now, in the next program, I have removed the subclassings,
>> there is no inheritance from the base class "Language"
>> anymore. Yet the polymorphism in "f" still work
r...@zedat.fu-berlin.de (Stefan Ram) writes:
> Julieta Shem writes:
>>Any book recomendations on getting this thing mathematics-clear?
>
> OOP cannot be mathematics-clear because it is an /attempt/ to
> abstract from several different programming languages.
>
> When you ask Alan Kay (and I
Greg Ewing writes:
> On 2/11/22 9:54 am, Julieta Shem wrote:
>> But we've left behind a more basic requirement --- the Stack
>> class wishes for all the methods already written in some class called
>> Pair,
>
> Is that *really* what you want, though?
>
> To my way of thinking, a Stack and a Pair
On 02/11/2022 20:21, Dennis Lee Bieber wrote:
>> shows that in Python we do *not* need subclassing/inheritance
>> for polymorphism!
>>
> To me, that is not really an example of polymorphism, but more an
> example of Python's "duck typing".
But duck typing is a perfectly good implementatio
On 01/11/2022 17:58, Julieta Shem wrote:
> nowhere in trying to detect in high-precision what is OOP and what is
> not.
Stefan has given a good answer but essentially OOP is a program
that is structured around objects communicating by sending
messages to one another.
Objects are, in most (but n
On 2/11/22 9:54 am, Julieta Shem wrote:
But we've left behind a more basic requirement --- the Stack
class wishes for all the methods already written in some class called
Pair,
Is that *really* what you want, though?
To my way of thinking, a Stack and a Pair are quite different
data structures
r...@zedat.fu-berlin.de (Stefan Ram) writes:
> r...@zedat.fu-berlin.de (Stefan Ram) writes:
>>The crucial feature OOP adds to this is polymorphism ("late binding").
>
> If polymorphism is so crucial, the idea of subclasses
> has something to it! [...]
I wonder what Rich Hickey would say here
r...@zedat.fu-berlin.de (Stefan Ram) writes:
> Julieta Shem writes:
>>clarify. If I wish for an empty stack, I wish I could just say
> Stack()
>>Stack()
>>and if I wish for a nonempty stack, I'd write
> Stack(1, Stack(2, Stack(3, Stack(
>>Stack(1, Stack(2, Stack(3, Stack(
>
> I
22 at 3:43 PM
To: python-list@python.org
Subject: Re: an oop question
*** Attention: This is an external email. Use caution responding, opening
attachments or clicking on links. ***
Julieta Shem writes:
>clarify. If I wish for an empty stack, I wish I could just say
>>>> Stack()
Alan Gauld writes:
> On 30/10/2022 14:01, Julieta Shem wrote:
>
>> I wrote the classes
>>
>> class Empty:
>> ...
>> class Pair:
>> ...
>>
>> (*) How to build a stack?
>>
>> These Lisp-like sequences are clearly a stack.
>
> That is a very important observation. A Pair IS-A Stack(
Chris Angelico writes:
> On Mon, 31 Oct 2022 at 14:38, Julieta Shem wrote:
>>
>> Chris Angelico writes:
>>
>> > The most straight-forward way to represent this concept in an
>> > object-oriented way is subclassing.
>> >
>> > class Stack:
>> > ... # put whatever code is common here
>> >
>> >
On 30/10/2022 14:01, Julieta Shem wrote:
> I wrote the classes
>
> class Empty:
> ...
> class Pair:
> ...
>
> (*) How to build a stack?
>
> These Lisp-like sequences are clearly a stack.
That is a very important observation. A Pair IS-A Stack(sort of).
If you had a stack you coul
On Mon, 31 Oct 2022 at 14:38, Julieta Shem wrote:
>
> Chris Angelico writes:
>
> > The most straight-forward way to represent this concept in an
> > object-oriented way is subclassing.
> >
> > class Stack:
> > ... # put whatever code is common here
> >
> > class Empty(Stack):
> > ... # pu
Chris Angelico writes:
> On Mon, 31 Oct 2022 at 09:05, Julieta Shem wrote:
>>
>> Julieta Shem writes:
>>
>> [...]
>>
>> >> . If you should, however, be talking about the new "type hints":
>> >> These are static and have "Union", for example, "Union[int, str]"
>> >> or "int | str".
>> >
>>
On 31/10/2022 09.22, Stefan Ram wrote:
Giorgio Pastore writes:
You may find useful to learn about the possibilities of using Python
tools to implement a stack data structure and its manipulation methods.
A good introduction is at
https://realpython.com/how-to-implement-python-stack/
I can'
same interface create an abstract base class and derive both
of them from it.
https://docs.python.org/3/library/abc.html
From: Python-list on
behalf of Julieta Shem
Date: Sunday, October 30, 2022 at 5:51 PM
To: python-list@python.org
Subject: an oop question
*** Attention: This is an
On Mon, 31 Oct 2022 at 09:05, Julieta Shem wrote:
>
> Julieta Shem writes:
>
> [...]
>
> >> . If you should, however, be talking about the new "type hints":
> >> These are static and have "Union", for example, "Union[int, str]"
> >> or "int | str".
> >
> > I ended up locating such features
Il 30/10/22 15:54, Julieta Shem ha scritto:
r...@zedat.fu-berlin.de (Stefan Ram) writes:
Julieta Shem writes:
My desire seems to imply that I need a union-like data structure.
You only need to worry about such things in languages with
static typing. For example, to have a function tha
Julieta Shem writes:
[...]
>> . If you should, however, be talking about the new "type hints":
>> These are static and have "Union", for example, "Union[int, str]"
>> or "int | str".
>
> I ended up locating such features of the language in the documentation,
> but I actually am not interes
r...@zedat.fu-berlin.de (Stefan Ram) writes:
> Julieta Shem writes:
>>My desire seems to imply that I need a union-like data structure.
>
> You only need to worry about such things in languages with
> static typing. For example, to have a function that can
> sometimes return an int value an
I have a question about a particular case I'm working on. I'm studying
OOP. To ask the question, I'm going to have to introduce you my context
here, so you'll need to bear with me. If you'd like to see the question
right away, go to the section ``My difficulty in encapsulating a
union''.
(*) In
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