On 17 Nov, 19:58, Carl Banks [EMAIL PROTECTED] wrote:
Google for Liskov Substitutability if you are interested. I didn't pull
this idea out of my hat. In fact I learned the term from reading a post
by GvR himself, though the idea was intuitive to me long before that.
Carl Banks
On 16 Nov, 16:35, Carl Banks [EMAIL PROTECTED] wrote:
On Thu, 15 Nov 2007 21:25:16 -0800, Dennis Lee Bieber wrote:
On Thu, 15 Nov 2007 16:57:57 -0800 (PST), Carl Banks
[EMAIL PROTECTED] declaimed the following in comp.lang.python:
A source of confusion with is a is that it doesn't
Well, you would if you override the two set_* methods to set both
height and width to the same value G
But that breaks expectations: a user doesn't expect set_width() to
affect
the height.
I can't speak for everyone but I certainly expect setting the width of
a Square to change
On 2007-11-17, Odalrick [EMAIL PROTECTED] wrote:
But that breaks expectations: a user doesn't expect
set_width() to affect the height.
I can't speak for everyone but I certainly expect setting the
width of a Square to change it's height. In fact, that would
probably be the reason I used a
[EMAIL PROTECTED] a écrit :
In learning about design patterns, I've seen discussion about using
inheritance when an object's relationship to another object is 'is-a'
and composition when the relationship is 'has-a'.
wrt/ inheritance, it only makes sens with declarative static type
systems
[EMAIL PROTECTED] a écrit :
(snip)
It's hard to apply some of the available
material's examples to Python since a lot of the documentation I find
is specific to implementations in lower-level languages and don't
apply to Python.
Fact is that quite a few design patterns are mostly workaround
On 2007-11-15, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
inheritance when an object's relationship to another object is 'is-a'
and composition when the relationship is 'has-a'.
Since this is all new and I'm still learning, I was hoping someone can
give me some pointers on best practices on
On 2007-11-16, Dennis Lee Bieber [EMAIL PROTECTED] wrote:
On Thu, 15 Nov 2007 12:28:28 -0800 (PST), [EMAIL PROTECTED]
[EMAIL PROTECTED] declaimed the following in comp.lang.python:
As a very simplified example, if I had two classes, Pet and Owner, it
seems that I would not have Pet inherit
In learning about design patterns, I've seen discussion about using
inheritance when an object's relationship to another object is 'is-a'
and composition when the relationship is 'has-a'.
Since this is all new and I'm still learning, I was hoping someone can
give me some pointers on best
As a very simplified example, if I had two classes, Pet and Owner, it
seems that I would not have Pet inherit from Owner, since a pet 'has
an' owner, but not 'is an' owner. If this is correct, does my code
below reflect this? I passed the owner object into the pet object's
constructor - is
On Nov 15, 3:37 pm, Diez B. Roggisch [EMAIL PROTECTED] wrote:
Also, I've seen talk that ideally you shouldn't have too many dots
in your method calls, instead using delegates to the methods and
attributes. Can anyone elaborate on this? Ideally, should I be writing
getattr() methods so I
Yes. Of course there are other ways, establishing the connection later,
and of course making the Owner know her pets. But your unidirectional,
ctor-passed implementation is sensible.
I think my main concern while getting my toes wet on this was to not
reference the owner object out of thin air
Sorry for the double post
-- Forwarded message --
From: Matthieu Brucher [EMAIL PROTECTED]
Date: 15 nov. 2007 23:38
Subject: Re: Python Design Patterns - composition vs. inheritance
To: [EMAIL PROTECTED] [EMAIL PROTECTED]
2007/11/15, [EMAIL PROTECTED] [EMAIL PROTECTED
On Nov 15, 2007 2:37 PM, Diez B. Roggisch [EMAIL PROTECTED] wrote:
As a very simplified example, if I had two classes, Pet and Owner, it
seems that I would not have Pet inherit from Owner, since a pet 'has
an' owner, but not 'is an' owner. If this is correct, does my code
below reflect
I think my main concern while getting my toes wet on this was to not
reference the owner object out of thin air but to pass it in when
pet is instantiated. I'm not sure what 'actor-passed' is yet, but it
gives me something to search for and learn about.
I meant ctor, short-hand for
On Nov 15, 3:28 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
My response ended up being pretty long and heavy for a beginner, but
you sound pretty smart.
In learning about design patterns, I've seen discussion about using
inheritance when an object's relationship to another object is
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