amcgregor/00-irc-log.textile

## 00-irc-log.textile

      
    Raw
  

              00-irc-log.textile
            
          
    Cleaned IRC log of #python starting Monday, 25 July, 2011 at 17:13:55 EDT.
Gems are highlighted in bold.

	
		GothAlice 
		 How do I determine if a given object is a @classmethod, and, additionally, how do I determine if it is a @staticmethod? ¹ 
	
	
		KirkMcDonald 
		 GothAlice: Why would you care? 
	
	
		GothAlice 
		 KirkMcDonald: Enforcing interfaces, not that it matters. 
	
	
		dash 
		 GothAlice: you’re right, it doesn’t matter 
	
	
		_habnabit 
		 GothAlice, if you wanted an answer to the question as asked, why don’t you try ##python-friendly? #python is about writing better code. 
	
	
		nedbat 
		 GothAlice: what KirkMcDonald should have said was, “The Python culture is to not check ahead of time, do you have an unusual requirement that means you really have to know?” 
	
	
		GothAlice 
		 _habnabit: Cute, thank you for living up to expectations. 
	
	
		nedbat 
		 _habnabit: you don’t have to treat people that way. 
	
	
		GothAlice 
		 nedbat: Assume yes, I do have a requirement that needs this. 
	
	
		message144 
		 heh today i learned that ##python-friendly is a real thing 
	
	
		GothAlice 
		 nedbat: No worries, I expect that kind of behaviour from him and a few select others. 
	
	
		nedbat 
		 GothAlice: the inspect module has lots of tools, not sure if it covers what you’re looking for. 
	
	
		GothAlice 
		 nedbat: I’ve already looked, it doesn’t. 
	
	
		GothAlice 
		 Also, _habnabit, it’s against channel rules to advertise other channels; or it was, last time I checked. 
	
	
		KirkMcDonald 
		 GothAlice: The answer is obvious if you know how classmethod and staticmethod work. ² 
	
	
		nedbat 
		 KirkMcDonald: that’s not that helpful an answer either. 
	
	
		GothAlice 
		 KirkMcDonald: Again, thank you for meeting expectations.  Is it any wonder I created ##python-friendly? 
	
	
		KirkMcDonald 
		 GothAlice: Just yank the objects out of the thing and see what they are. ² 
	
	
		GothAlice 
		 KirkMcDonald: Still not helpful.  You do realize you’re wasting not just my time, but yours as well? 
	
	
		dash 
		 GothAlice: You already know what to expect when you come here. 
	
	
		nedbat 
		 dash: why is it ok for her to expect curt rude unhelpful answers? 
	
	
		dash 
		 GothAlice: So please don’t expect us to be moved by your complaints about it. 
	
	
		Yhg1s 
		 nedbat: there’s quite a bit of history involved. 
	
	
		dash 
		 nedbat: A long history of disagreement. 
	
	
		nedbat 
		 Yhg1s: I’m getting that sense, but in my experience, GothAlice is not unusual in this regard.  Lots of people have come to expect those answers. 
	
	
		KirkMcDonald 
		 nedbat: We’re not here to just answer asked questions. 
	
	
		Yhg1s 
		 nedbat: if the questions are about bad ideas, then yes, many people won’t give direct answers. With good reason. All too often, if they are given something that does what they seem to want, it’ll just ruin their design and they’ll come back crying later. 
	
	
		Yhg1s 
		 nedbat: #python is about helping people write Python, not get something working. 
	
	
		nedbat 
		 i’ve heard all this before.  Some people disagree.  I won’t take more of your time. 
	
	
		GothAlice 
		 I think that’s the primary conflict, here.  I feel no need to justify myself when asking a question about a real problem I’m encountering.  I’ve been programming commercially since I was 9, and generally my OSS code speaks for itself.  I’m not an idiot, don’t treat me as one. 
	
	
		Yhg1s 
		 nedbat: this is why there’s other channels :) 
	
	
		Yhg1s 
		 GothAlice: And yet you insist on treating us as idiots. Thanks. ³ 
	
	
		GothAlice 
		 However, my particular use case involves writing an interface declaration and enforcement system, similar to zope.interface, but a fair bit simpler. 
	
	
		KirkMcDonald 
		 GothAlice: If you find that you actually need to do this sort of metaprogramming nonsense, I am surprised you don’t know how to do it. ⁴ 
	
	
		nedbat 
		 KirkMcDonald: we’ve established that you are surprised.  Now, do you know the answer? 
	
	
		KirkMcDonald 
		 That you have sufficient skill for this kind of metaprogramming to be a need but insufficient skill to just do it is strange to me. ⁴ 
	
	
		dash 
		 GothAlice: I would note that not even zope.interface checks if things are staticmethods or classmethods. :) 
	
	
		KirkMcDonald 
		 I gave the answer: Get the objects. See what they are instances of. ² 
	
	
		dash 
		 GothAlice: So your approach already sounds less simple 
	
	
		GothAlice 
		 sighs. 
	
	
		nedbat 
		 KirkMcDonald:  when i get a classmethod from an object, its type is “instancemethod”. 
	
	
		NelleV 
		 GothAlice: maybe you’ll have more answers on the python-list mailing list 
	
	
		Yhg1s 
		 nedbat: you have to get it from the class, of course. 
	
	
		KirkMcDonald 
		 To get the actual classmethod object, you don’t even get it from the class. You need to sidestep the descriptor protocol. 
	
	
		Yhg1s 
		 some knowledge of how these things work is necessary, if you want to do these kinds of things. There’s several decent documents on the interwebs that explain how classes, metaclasses and descriptors like staticmethod and classmethod work. [17:29:43] 
	
	
		GothAlice 
		 Yhg1s: A ha, descriptor protocol.  Thank you for finally being useful.  type(obj).mro() + dict here I come. ⁵ 
	
	
		Yhg1s 
		 GothAlice: ‘finally being useful’. Thanks again. 
	
	
		Yhg1s 
		 GothAlice: your hostile attitude is as old as your passive-agressiveness. Please go away, learn to act like a civil person or ask better questions (preferably all three.) ⁶ 
	
	
		GothAlice 
		 Yhg1s: Just giving credit where credit is due.  Those two words took 15 minutes and solved my problem.  Additionally, the question was perfectly sound.  Your insistence on correcting the purpose of others’ code is the problem. 
	
	
		Kaedenn 
		 GothAlice: Welcome to #python 
	
	
		Kaedenn 
		 GothAlice: I see you’re new here 
	
	
		17:33:40 
		 mode (+o Yhg1s) by ChanServ 
	
	
		17:33:51 
		 mode (+b !amcgregor@74.198.165.*) by Yhg1s 
	
	
		17:33:52 
		 You have been kicked by Yhg1s: (Don’t come back.) 
	

¹ If you can argue that this isn’t a clear and concise question, please comment.
² Snide and/or unhelpful answers that are such in any context.  Pretend you’re a tourist, and from everyone you ask “How do I get to X?” you get “Well, if you lived here, you’d know!”
³ Not sure how dismissing useless answers is treating someone as an idiot… sure, repeatedly pointing out someone is living up to low expectations (held not just by me) might be insulting, but when it’s demonstrated again and again—within the same conversation no less—it’s not unjustified.
⁴ These aren’t even subtle.
⁵ Should have been directed at KirkMcDonald and Yhg1s.
⁶ Prior to the actual answer there was one attempted good-faith answer (inspect module, alas, not viable), two dismissals, three purposefully vague and unhelpful answers, at least two thinly veiled insults, and three suggestions to ask elsewhere (though one was more along the lines of “You know we won’t help you, so why do you bother?”).
This is not a good sign for what one might usually refer to as a “Python support community”.  Operative word being support.  Thank you, nedbat, for helping.  The inspect module, after further inspection, does contain code that can be helpful by way of the undocumented classify_class_attrs function, which works in much the same way as my own code.
For future reference, the solution is attached.
  

## 02-solution.py
def isclassmethod(cls, name):
    for cls in cls.mro():
        if name in cls.__dict__:
            if type(cls.__dict__[name]) is classmethod:
                return True

            return False

    return False

def isstaticmethod(cls, name):
    for cls in cls.mro():
        if name in cls.__dict__:
            if type(cls.__dict__[name]) is staticmethod:
                return True

            return False

    return False


class Foo(object):
    def foo(self):
        pass

    @classmethod
    def bar(cls):
        pass

    @staticmethod
    def baz():
        pass


assert not isclassmethod(Foo, 'foo'), "Method is classmethod?"
assert isclassmethod(Foo, 'bar'), "Classmethod isn't?"
assert isstaticmethod(Foo, 'baz'), "Staticmethod isn't?"
GothAlice	How do I determine if a given object is a @classmethod, and, additionally, how do I determine if it is a @staticmethod? ¹
KirkMcDonald	GothAlice: Why would you care?
GothAlice	KirkMcDonald: Enforcing interfaces, not that it matters.
dash	GothAlice: you’re right, it doesn’t matter
_habnabit	GothAlice, if you wanted an answer to the question as asked, why don’t you try ##python-friendly? #python is about writing better code.
nedbat	GothAlice: what KirkMcDonald should have said was, “The Python culture is to not check ahead of time, do you have an unusual requirement that means you really have to know?”
GothAlice	_habnabit: Cute, thank you for living up to expectations.
nedbat	_habnabit: you don’t have to treat people that way.
GothAlice	nedbat: Assume yes, I do have a requirement that needs this.
message144	heh today i learned that ##python-friendly is a real thing
GothAlice	nedbat: No worries, I expect that kind of behaviour from him and a few select others.
nedbat	GothAlice: the inspect module has lots of tools, not sure if it covers what you’re looking for.
GothAlice	nedbat: I’ve already looked, it doesn’t.
GothAlice	Also, _habnabit, it’s against channel rules to advertise other channels; or it was, last time I checked.
KirkMcDonald	GothAlice: The answer is obvious if you know how classmethod and staticmethod work. ²
nedbat	KirkMcDonald: that’s not that helpful an answer either.
GothAlice	KirkMcDonald: Again, thank you for meeting expectations. Is it any wonder I created ##python-friendly?
KirkMcDonald	GothAlice: Just yank the objects out of the thing and see what they are. ²
GothAlice	KirkMcDonald: Still not helpful. You do realize you’re wasting not just my time, but yours as well?
dash	GothAlice: You already know what to expect when you come here.
nedbat	dash: why is it ok for her to expect curt rude unhelpful answers?
dash	GothAlice: So please don’t expect us to be moved by your complaints about it.
Yhg1s	nedbat: there’s quite a bit of history involved.
dash	nedbat: A long history of disagreement.
nedbat	Yhg1s: I’m getting that sense, but in my experience, GothAlice is not unusual in this regard. Lots of people have come to expect those answers.
KirkMcDonald	nedbat: We’re not here to just answer asked questions.
Yhg1s	nedbat: if the questions are about bad ideas, then yes, many people won’t give direct answers. With good reason. All too often, if they are given something that does what they seem to want, it’ll just ruin their design and they’ll come back crying later.
Yhg1s	nedbat: #python is about helping people write Python, not get something working.
nedbat	i’ve heard all this before. Some people disagree. I won’t take more of your time.
GothAlice	I think that’s the primary conflict, here. I feel no need to justify myself when asking a question about a real problem I’m encountering. I’ve been programming commercially since I was 9, and generally my OSS code speaks for itself. I’m not an idiot, don’t treat me as one.
Yhg1s	nedbat: this is why there’s other channels :)
Yhg1s	GothAlice: And yet you insist on treating us as idiots. Thanks. ³
GothAlice	However, my particular use case involves writing an interface declaration and enforcement system, similar to zope.interface, but a fair bit simpler.
KirkMcDonald	GothAlice: If you find that you actually need to do this sort of metaprogramming nonsense, I am surprised you don’t know how to do it. ⁴
nedbat	KirkMcDonald: we’ve established that you are surprised. Now, do you know the answer?
KirkMcDonald	That you have sufficient skill for this kind of metaprogramming to be a need but insufficient skill to just do it is strange to me. ⁴
dash	GothAlice: I would note that not even zope.interface checks if things are staticmethods or classmethods. :)
KirkMcDonald	I gave the answer: Get the objects. See what they are instances of. ²
dash	GothAlice: So your approach already sounds less simple
GothAlice	sighs.
nedbat	KirkMcDonald: when i get a classmethod from an object, its type is “instancemethod”.
NelleV	GothAlice: maybe you’ll have more answers on the python-list mailing list
Yhg1s	nedbat: you have to get it from the class, of course.
KirkMcDonald	To get the actual classmethod object, you don’t even get it from the class. You need to sidestep the descriptor protocol.
Yhg1s	some knowledge of how these things work is necessary, if you want to do these kinds of things. There’s several decent documents on the interwebs that explain how classes, metaclasses and descriptors like staticmethod and classmethod work. [17:29:43]
GothAlice	Yhg1s: A ha, descriptor protocol. Thank you for finally being useful. type(obj).mro() + dict here I come. ⁵
Yhg1s	GothAlice: ‘finally being useful’. Thanks again.
Yhg1s	GothAlice: your hostile attitude is as old as your passive-agressiveness. Please go away, learn to act like a civil person or ask better questions (preferably all three.) ⁶
GothAlice	Yhg1s: Just giving credit where credit is due. Those two words took 15 minutes and solved my problem. Additionally, the question was perfectly sound. Your insistence on correcting the purpose of others’ code is the problem.
Kaedenn	GothAlice: Welcome to #python
Kaedenn	GothAlice: I see you’re new here
17:33:40	mode (+o Yhg1s) by ChanServ
17:33:51	mode (+b !amcgregor@74.198.165.*) by Yhg1s
17:33:52	You have been kicked by Yhg1s: (Don’t come back.)
	def isclassmethod(cls, name):
	for cls in cls.mro():
	if name in cls.__dict__:
	if type(cls.__dict__[name]) is classmethod:
	return True

	return False

	return False

	def isstaticmethod(cls, name):
	for cls in cls.mro():
	if name in cls.__dict__:
	if type(cls.__dict__[name]) is staticmethod:
	return True

	return False

	return False


	class Foo(object):
	def foo(self):
	pass

	@classmethod
	def bar(cls):
	pass

	@staticmethod
	def baz():
	pass


	assert not isclassmethod(Foo, 'foo'), "Method is classmethod?"
	assert isclassmethod(Foo, 'bar'), "Classmethod isn't?"
	assert isstaticmethod(Foo, 'baz'), "Staticmethod isn't?"