The Whiteboard - 2015-12-29 (page 2 of 5)

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2:05 PM

May I submit that this edit is important because it clarifies that the asker does not merely mean "class methods", but rather any method in a class: programmers.stackexchange.com/review/suggested-edits/127486

Happy Coffee Day

@AaronHall I had no idea "class method" meant anything other than "a method a class has", is google correct in telling me that it actually means "static method"?

no, I would distinguish between a static method and a class method

Lightness Races in Orbit

@AaronHall What's the distinction?

a class method is a member function, no?

My reference point is Python

2:08 PM

well now I'm hopelessly confused

I declare this terminology stupid

A static method does not know its class

A class method does

@gnat very cool; this lends a lot of credence to the idea of SO limiting sending them here. I do recall when SO burned down their close queue, I still wouldn't call this conclusive - the debugging questions seems to have spiked more in the last 2-3 months from my perspective but perhaps I'm just not looking close enough. Still seems likely you're right based on that and a lack of evidence supporting any other theory

Lightness Races in Orbit

Method (computer programming)

A method (or message) in object-oriented programming (OOP) is a procedure associated with an object class. An object is made up of behavior and data. Data is represented as properties of the object and behavior as methods. Methods are also the interface an object presents to the outside world. For example a window object would have methods such as open and close. One of the most important capabilities that a method provides is method overriding. The same name (e.g., area) can be used for multiple different kinds of classes. This allows the sending objects to invoke behaviors and to delegate the...

TIL

An instance method knows its instance (and thus its class)

Lightness Races in Orbit

@AaronHall wait what

2:09 PM

@AaronHall ...what does that even mean?

@LightnessRacesinOrbit were you unfamiliar with the term?

Lightness Races in Orbit

@JimmyHoffa The onebox broke the link - it's actually to a subcategory

the only interpretation I can come up with is "a class method doesn't use this" which would make it synonymous with instance method

Lightness Races in Orbit

Regardless, I think what we're discovering here is that we'd better avoid the term "method" entirely for being hopelessly ambiguous. That's what we do in C++. Member function, static member function. End of!

@LightnessRacesinOrbit oh yeah; "class method" and "instance method" are two distinctions I learned a couple years ago too after a big "the hell you talking about?"

2:11 PM

a method that has no idea what class it's a method of...is not even a method anymore, or at most it's a method of some utility class associated with another class

I guess

different language cultures use different terms for the same things

My favorite useful static method in Python is the str.maketrans method in Python 3.

@AaronHall if it helps, I did check the question for language tags before rejecting, and I've never heard any of this terminology in the context of Javascript so it seemed safe to assume it wasn't some weird C# thing

@Ixrec this stuff all depends on your perspective.. the actual mechanics at play are something I suspect everyone here is familiar with. Just the approach to explaining it is tinged by your language culture. For example, nobody anywhere in .NET would ever use the term "class method" because it makes no feckin sense at all and sounds stupid, but it's a totally standard term in I think ruby? and others

Lightness Races in Orbit

JavaScript doesn't have classes anyway so wtf

2:13 PM

what question?

@JimmyHoffa I'm still waiting for a coherent definition of what the term means in any context, lol

>>> 'abracadabra'.translate(str.maketrans('abc', 'bca'))
'bcrbabdbcrb'

@LightnessRacesinOrbit large portion of folk are still convinced it's an "OO" language and because of their misguided sense of both that and what "OO" is they presume JS both has classes and just calls them something else

Lightness Races in Orbit

@JimmyHoffa Yes I think we can agree those people are wrong

also because JS itself is confused about it

2:14 PM

@Ixrec in some languages they call static methods "class" methods because it's not associated with an instance, and non-static methods are "instance" methods

Lightness Races in Orbit

You can kind of fake classes in JS by abusing its prototype-based OO

@JimmyHoffa that's terribad

str.maketrans creates a dictionary. It has no reason to know it's attached to the str object.

@LightnessRacesinOrbit I completely agree, but it's seen as the height of recognition and comprehension of "OO" among some languages; if a Rubyist asked you about those terms and you looked confused it would be the same as if you asked someone the difference between static and non-static methods and they looked confused: You'd think them an incompetent

different language cultures, different terms, same concepts

before Python 3, you had to import it from the string module

@AaronHall so is Python also use the "class" vs "instance" method terminology?

2:16 PM

So it's a static method

@JimmyHoffa that was my first guess, then Aaron said that was wrong and gave me an alternative I couldn't parse, which is why I'm confused

Here's my favorite example of a class method:

@Ixrec well, perhaps I have it wrong too... I don't know, it is a genuinely terrible term

>>> dict.fromkeys('abc')
{'a': None, 'c': None, 'b': None}

it knows its class, it has no instance, it's creating a new instance.

@AaronHall if I knew Python I might understand what makes that a class method..

I mean, that doesn't even look like a method definition to me

Lightness Races in Orbit

2:17 PM

what's this "knows its class" concept?

dict.fromkeys is a class method

oh

what Lightness said, that's the part I'm waiting for

dict.fromkeys is a function of the class that is creating it

Lightness Races in Orbit

yes...

2:19 PM

@Ixrec in normal languages static methods "know" their class insofar as they have access to private static information

Lightness Races in Orbit

can you show me an example of a method that doesn't "know its class"

@LightnessRacesinOrbit Python is procedural - it can have free functions

Lightness Races in Orbit

@JimmyHoffa ... which aren't methods then ...

>>> from collections import OrderedDict
>>> OrderedDict.fromkeys('abc')
OrderedDict([('a', None), ('b', None), ('c', None)])

@AaronHall what is "it"? the way you wrote that sentence, "it" would have to be the fromkeys function, which makes no sense

Lightness Races in Orbit

2:20 PM

are we using "method" to mean "any function" now?

perhaps that's why they have this terribad terminology - languages with free functions have community's that tried to parse 3 different types of functions

@LightnessRacesinOrbit in Python maybe? I don't bloody know..

Lightness Races in Orbit

@AaronHall o.O

what's dict in your previous example

@AaronHall show a method definition that "knows it's class" perhaps maybe it will become clearer what you mean then?

@LightnessRacesinOrbit see chat.stackexchange.com/transcript/message/26479119#26479119

8 mins ago, by Aaron Hall

>>> 'abracadabra'.translate(str.maketrans('abc', 'bca'))
'bcrbabdbcrb'

@JimmyHoffa why does the existence of "free functions" make it hard to say "free functions", "static methods" and "instance methods"?

Lightness Races in Orbit

2:21 PM

I see it but it still doesn't explain anything to me

str.maketrans is a static method

Lightness Races in Orbit

ok

what's OrderedDict.fromkeys if not a [free] function or a static method?

It's attached to the object for convenience

@Ixrec don't ask me! I'm just theorizing here why they have terminology that aligns in no way with any other language cultures

@LightnessRacesinOrbit that's a class method, it knows its class

Lightness Races in Orbit

2:22 PM

@JimmyHoffa lol

@AaronHall Repeating the same terminology doesn't help in explaining it :(

@Ixrec That wouldn't be Pythonic, would it?

a class method is a function of the class, an instance method is a function of the instance

@Yannis does PHP use the "class" method vs. "instance" method terminology as well?

I know there are multiple language cultures that do use such terms I believe

Lightness Races in Orbit

ok apparently I don't know Python at all. I have no idea what the distinction is between the two.

@AaronHall we understand static vs non-static, it's the other distinction you're making that you still haven't provided an explanation for

Lightness Races in Orbit

2:24 PM

In my world, you have free functions, and you have static "methods" and non-static "methods" and that's it.

I'm looking at the docs for dict.fromkeys() and str.maketrans() and I'm not seeing it either

@classmethod
def a_class_method(cls, x, y, z=None): ''

def a_instance_method(self, x, y, z=None): ''

@JimmyHoffa No. The terminology follows Java's.

@LightnessRacesinOrbit I think he's using the term class the way we use the term type because Python doesn't have a static type system so they perhaps lack terminology around the concepts of types

@AaronHall again, that's not the part we're confused about

Lightness Races in Orbit

2:24 PM

hey I've just had an excellent rep gathering idea :D

@AaronHall you're the one who said class method != static method

Well I'm trying to keep up...

@AaronHall so it becomes a class method just by putting "@classmethod" above it's definition?

ok, staticmethod:

does cls mean something special?

2:25 PM

@staticmethod
def a_static_method(x, y, z=None): ''

Yes, cls is the class that it is a function of

@AaronHall how do you then call that?

cls.classmethod(x, y)

no no, the static method

cls.a_static_method(x, y)

... ?? those are identical

2:27 PM

or instance.a_static_method(x, y)

wait, so str.maketrans is a class method and not a static method because its arguments are strings? is that it?

@AaronHall oh wait - a static method can be called on any class or instance?

they look identical, but there's a dotted lookup, and the decorators use descriptors to determine what the first argument is (or isn't...)

so it's a free function with syntactic sugar to make it look like it's a member of other things

You can call a class method on an instance

you can't use an instance method on a class.

2:28 PM

@AaronHall but can you call a static method on any class or instance? I mean, your static method definition didn't specify a class

1225

Q: What is the difference between @staticmethod and @classmethod in Python?

What is the difference between a function decorated with @staticmethod and one decorated with @classmethod?

python decorator static-methods class-method

cls.an_instance_method(x, y) would raise an error

Lightness Races in Orbit

@Ixrec dammit

0

Q: What are "class methods" and "instance methods", in Python?

There has been a discussion in chat relating to a question (the question itself being irrelevant to this one), that has revealed I may not know Python whatsoever. In my mind, although terminology differs across languages, we may generally categorise functions as: [free] functions static method...

python terminology

lol

> With classmethods, the class of the object instance is implicitly passed as the first argument instead of self.

@JimmyHoffa Yes

2:29 PM

wait, self isn't the class of the object instance?

are we passing types around instead of objects?

self implies instance

@Ixrec they don't have a type system so I don't think they use the term "type" - I think "class" means type to them

or is the "class" a special instance that has only the non-instance methods?

and I have discovered why they don't call class methods "static" methods, they apparently call free functions static methods, because they have a way of making any free function accessible as if it were a member of anything

Lightness Races in Orbit

u srs

2:30 PM

what I just linked completely contradicts the possibility that static method == free function

I have an answer on that link. :)

@Ixrec he just said you can call it on any class or instance, it isn't a member of anything but pretends to be a member of everything... that's a free function with syntactic sugar

Lightness Races in Orbit

Isn't it obvious? — Yannis ♦ 14 secs ago

dafuq seriously

hey, I'm allowed to troll every now and then

> They behave like plain functions except that you can call them from an instance or the class:

Lightness Races in Orbit

2:31 PM

MOD ABUSE CALL THE - ER....

if it were obvious do you really think we'd be having this conversation

@Ixrec your link supports my position. They have syntactic sugar to make free functions pretend to be methods, and then they call them "static" methods. class methods are what the rest of us call static methods, and instance methods are what the rest of us call "methods"

Lightness Races in Orbit

@JimmyHoffa if this is correct it's a very good way of putting it. To the answermobile!!

a.static_foo(1) doesn't look like a free function to me

@Ixrec it is though

it's defined without any type or instance

Lightness Races in Orbit

that's so wonky

2:33 PM

yeah, it's just sugar..

Lightness Races in Orbit

did those sorts of "methods" predate proper methods in Python?

I can see it being historical

but it is defined as part of a class

@Ixrec no it's not

Lightness Races in Orbit

@Ixrec apparently not

now it sounds like you're arguing free functions == static methods in all languages

ok, in the thing I linked it is

Lightness Races in Orbit

2:34 PM

he's not

@Ixrec no it's not

What's the smalltalk convention on this?

class A(object):
@staticmethod
def static_foo(x):
print "executing static_foo(%s)"%x

^it's part of A, isn't it?

Lightness Races in Orbit

@JimmyHoffa does look like it to me

the fact that it could have been declared outside of A doesn't change the fact that it isn't declared outside of A

2:36 PM

@Ixrec ok then. So it's...a function. I guess

has no access at all to anything in it's class, where a class method has access to other class information I guess?

Hey, at least it's not a monad.

@Yannis at least then I would know what the hell he was talking aboujt

You, sure. Anyone else? I doubt it.

Dec 14 at 17:45, by Jimmy Hoffa

Dec 7 at 17:07, by Jimmy Hoffa

Jul 27 at 13:30, by Jimmy Hoffa

Jul 14 at 15:02, by Jimmy Hoffa

@Ampt Have you accepted Haskell into your home, and into your heart?

anyway

now that I've found my way to the python docs on the @classmethod and @staticmethod decorators, it's now clear that these terms refer to real things that have definite meanings

the big remaining mystery is the cls thing that @classmethod generates, which those docs don't really say anything about

other than claiming it's "the class", which doesn't help much

does that mean it's a special object with all the non-instance methods of the class but no instance-y bits, or is there other magic going on?

2:41 PM

So, to me this edit is an important distinction: programmers.stackexchange.com/review/suggested-edits/127486

note that these terms are still totally meaningless in Javascript =)

but sure, I have nothing against someone else approving (it won't let me change my mind)

oh, and I'm going to answer that new question...

Lightness Races in Orbit

@AaronHall yay

I missed the deleted comment

Lightness Races in Orbit

didn't miss much

2:43 PM

ok :)

Lightness Races in Orbit

2:54 PM

ffs I hate when people delete their questions just as I'm answering them

arse

feedback welcome on my answer

Lightness Races in Orbit

meh still not clear

from either of them :(

don't show my CV to any of your Python guys ok

what's not clear?

Do I need to quote the question, and write more to the question?

Lightness Races in Orbit

I don't know because it's not clear to me

I'm still not getting this "knows its class" business

Was Jimmy right earlier about the syntactic sugar to make free functions behave as if they were members?

and am I at least right in saying that Python is batshit insane with a completely different notion and categorisation of "method" to everything else?

So a class method isn't static because members of the class can change (though they usually don't)

Lightness Races in Orbit

3:03 PM

wait what

@LightnessRacesinOrbit sort of.. I think because it's "in" the class, it is accessible as a member, but it has zero access to anything in that class - not other static methods or other class methods or anything. "class" methods however I think have access to other classmethods

a static method doesn't rely on the class

Lightness Races in Orbit

this is so completely different from how every other class-based language works :(

whyyyyyyy

@AaronHall You don't know Java or C# or C++ or any of the common static type system languages do you?

@LightnessRacesinOrbit Python started as a procedural language..

Lightness Races in Orbit

@JimmyHoffa So did C++

3:04 PM

I do not know their type systems

I've used Ruby a little, but it was a long time ago

@AaronHall you should learn one - it would help you communicate with a broader audience on some of these higher level concepts which you're clearly familiar with and understand

Lightness Races in Orbit

yeah

this whole conversation is cross talk because we don't know Python and you don't know any of the myriad type systems we're familiar with

Lightness Races in Orbit

I'm not cross

a little hungry perhaps

@LightnessRacesinOrbit you're a C++ coder; you're cross with everything and everyone

Lightness Races in Orbit

3:06 PM

@JimmyHoffa I'm cross cross

This is just executable pseudocode, what's the big deal?

just the other day you were yelling at a tea pot

:)

Lightness Races in Orbit

@JimmyHoffa that was a C pot

@LightnessRacesinOrbit C/C++

user55340

3:07 PM

@Yannis Isn't it pythonic.. don't you think?

user55340

(I'm sure I can come up with some awful lyrics for that...)

haha

1

Q: Does my design break modularity and loose coupling?

I want to know if my implementation is modular and loosely coupled such that pieces can be replaced easily. Any concrete class that extends the abstract class HexGridLayout will be expected to update the field coords by using the field center of the HexGrid. Does passing HexGrid to the HexGri...

design design-patterns object-oriented-design

^-- good question?

Lightness Races in Orbit

@MichaelT doooo itttttt!!

I think I fixed it.. I'm not sure whether it was fitting or not before

Lightness Races in Orbit

@JimmyHoffa hard to answer but looks on-topic

I enjoyed your original comment on the original

user55340

3:08 PM

@LightnessRacesinOrbit Thinking about it... some of the meter is just a bit awkward to work with.

Lightness Races in Orbit

@MichaelT if it helps you can use the common substitution s/python/whython/

I answered, but I get no love

@AaronHall I find Bryan Oakley's answer far clearer to be honest

The way you use the term "class" is very strange to me (probably totally normal for Python folk)

user55340

Hmm... my cat's pestivious meter is set to 11 today for some reason.

Lightness Races in Orbit

is it a class cat or an instance cat or a static cat

3:15 PM

@LightnessRacesinOrbit cats don't support that shit, they're all just free cats

user55340

Short hair, so the static cat isn't as prevalent.

@MichaelT temperature? Perhaps the frozingness demands more interaction with the various electrically heated devices nearby

Whenever it's cold outside and I let my dog out; when he comes back in the cold seems to have put a rocket up his butt because he flies in and runs circles around the house for like a minute, presumably trying to warm back up

user55340

Nov 20 '14 at 20:36, by MichaelT

Me and my cat.

Lightness Races in Orbit

@JimmyHoffa ok

yep definitely hungry

user55340

@JimmyHoffa heater in the room. Thermostat sensor says its 70F in here (I can get one room of the house comfortable). And its pestivious nature is that of "purr", rub up against me. One claw extended tap my hand.

user55340

3:18 PM

(just put some cat treats in a "you need to work at it to get them out" treat dispenser)

@MichaelT my cat would stand by that thing screaming his discontent until somebody gave it a treat

Lightness Races in Orbit

spoilt

user55340

Cats Playing with the Fun New Friskies Pull ‘n Play Cat Treat Toy

user55340

My cat doesn't care too much for the string part - but the hole in the side for getting a treat out... he's all for that.

Lightness Races in Orbit

ew

3:29 PM

updated my answer

Lightness Races in Orbit

@AaronHall gonna take me a while to read. hungry.

the difference from other languages seems to stem from classes being treated as first class objects. ish?

and static methods are really just free functions in the class's "namespace"

@Ixrec in Python, everything is an object. Including the class definition

So each instance object is an object, and they are instances of classes, which are also objects.

Lightness Races in Orbit

this would all make great interview discussion

gives me things to talk about while I'm explaining how I have written Python but don't really "know" it

>>> isinstance(object, object)
True
>>> class Object(object): ''
...
>>> instance = Object()
>>> isinstance(instance, Object)
True
>>> isinstance(instance, object)
True
>>> isinstance(Object, object)
True

object is an instance of type

and type is an object

>>> isinstance(object, type)
True
>>> isinstance(type, object)
True

type is the metaclass of object

So the class is an object that can be passed around as an argument

Lightness Races in Orbit

so "yes"

3:41 PM

Is that where the confusion comes from?

Lightness Races in Orbit

no

the confusion comes from you answering questions about terminology with the same terminology :P

but your answer is better now

ok, ask me more questions or tell me how to improve it

Use more and different terminology?

Lightness Races in Orbit

I think Jimmy summed it up pretty well

We've probably taken this as far as we can without a common language

a line at the top saying "forget everything you think you know about 'methods' from other languages" would be the icing on the cake for the first-time reader

to go back to your initial question, then, the edit seems fine if you explain in the reason that it's due to ambiguity with Python's bizarre "method" concept, and check that that's really what the OP (who may be a Pythonista) meant

I don't know if "forget everything you think you know about 'methods' from other languages" is quite right

Lightness Races in Orbit

pretty sure it is

meanwhile I was hoping for more love on the question itself :( sadface

did I mention I'm hungry

3:53 PM

mmmm bagel and lox

want one?

user55340

Whee! Present for me from me in the mail.

Lightness Races in Orbit

nah gonna oven cook some chicken dippers I think

it's amazing how many people are now "remembering Lemmy". didn't realise until today that any of them had actually met him let alone knew him

What if I had said, "remember math class? y is a function of x (f(x))? well a classmethod is a function of the class"

Lightness Races in Orbit

probably not useful as I can't see how you'd maintain that analogy while describing instance and static methods

and it's already pretty weak even for class methods

:P

What? It applies precisely the same!

an instance method is a function of the instance

A static method is a function of neither!

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