On 14Aug2019 11:15, Steven D'Aprano <st...@pearwood.info> wrote:
On Wed, Aug 14, 2019 at 09:58:35AM +1000, Cameron Simpson wrote:
On 11Aug2019 22:58, James Hartley <jjhart...@gmail.com> wrote:
>I am lacking in understanding of the @staticmethod property.
>Explanation(s)/links might be helpful. I have not found the descriptions
>found in the Internet wild to be particularly instructive.
You have received some answers; to me they seem detailed enough to be
confusing.
Its only confusing if you don't work your way through it carefully and
systematically. There's a lot to understand, but if you don't understand
it, Python's behaviour in this case seems counter-intuitive and hard to
follow.
Yeah, but it helps to understand the objective: function context.
A deep dive into the mechanisms used to achieve that is a load to
ingest. High levels of detail tend to swamp one's view of the larger
picture, particularly when learning.
[...]
I think of things this way: what context does a method require? Not
everything needs the calling instance.
Here endeth the lesson.
Given that you go on to write almost another 150 lines of explanation, I
think a better description would be "Here *begins* the lesson" *wink*
Well, maybe, but I really wanted to highlight the objective:
@classmethod and @staticmethod dictate the context provided to the
method.
All the examples that follow aim, however vaguely, to show those
contexts in action.
Your lesson, I think, assumes that it is obvious that staticmethods
don't have access to the calling instance, or its class.
No, it aims to make that point clear. EVerything else is example or
mechanism.
But if you look
at James' code, I think you will agree that he's assuming that
staticmethods *do* have access to the calling class, and is perplexed by
the fact that the look-up of class variables (class attributes) fails.
Because nobody had said that @staticmethod and @classmethod _define_ the
provided context.
Your lesson gives us no clue why James' first method, "dimensions()",
which he describes as a "class method", isn't a class method and doesn't
actually work correctly, even though it appears to at first glance.
I didn't try to tackle his code. I think it is better to get the
intended use of @classmethod and @staticmethod clear. Digging into
whatever weird consequences there might be to his slightly wrong code
just brings confusion.
Cheers,
Cameron Simpson <c...@cskk.id.au>
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