[Tutor] When to use classes

[boB Stepp]

On Sat, Aug 19, 2017 at 4:04 AM, Peter Otten <__peter__ at web.de> wrote:
> Steven D'Aprano wrote:
>
>> Mostly for Bob, but also for anyone else interested:
>>
>> When To Use Classes
>>
>> http://kentsjohnson.com/stories/00014.html
>
> Just a minor nit, but you don't even need a custom function for the callback
>
> result = []
> db.query(sql, result.append)
>
> The lesson is that Python already provides some powerful ready-to-use
> classes that take you a long way without having to write your own custom
> classes.

In my beginning experiments to date writing classes, I have often
while writing my toy examples realized, "Why am I writing a class?
Python already does this more straightforwardly with <insert Python
featured code here>."  Of course not knowing all of Python I sometimes
don't realize this until well after I wrote the unneeded class.

> Another alternative to (explicit) classes are generators which are an
> elegant way to hold state and provide a simple interface.
>
> In modern Python db.query() should be an iterable to that the above can be
> written
>
> result = list(db.query(sql))

I hope I don't forget this point between now and when I get the
database part of my project going!

> (That was easy; but I wonder what tkinter would look like without
> callbacks...)

I wish I knew more so that I could fully wonder about this myself.
You might even be making a clever joke and I am clueless.


>> - if you can't, encapsulate it in classes.
>
> I think it's important that you say "classes", not "class". As with
> functions three small dedicated classes are much better than one big know-
> it-all/do-it-all class.

I try to keep this in mind.  Another thing I'm currently struggling
with is when to use inheritance vs. separate, independent classes.


-- 
boB