I'm a big Python fan who used to be involved semi regularly in comp.lang.python (lots of lurking, occasional posting) but kind of trailed off a bit. I just wrote a frustration inspired rant on my blog, and I thought it was relevant enough as a wider issue to the Python community to post here for your discussion and consideration.
This is not flamebait. I love Python, and I'm not out to antagonise the community. I also realise that one of the issues I raise is way too ingrained to be changed now. I'd just like to share my thinking on a misstep in Python's guiding principles that has done more harm than good IMO. So anyway, here's the post.
I've become utterly convinced that at least one criticism leveled at my favourite overall programming language, Python, is utterly true and fair. After quite a while away from writing Python code, I started last night on a whim to knock up some code for a prototype of an idea I once had. It's going swimmingly; the Python Image Library, which I'd never used before, seems quick, intuitive, and with the all the features I need for this project. As for Python itself, well, my heart still belongs to whitespace delimitation. All the basics of Python coding are there in my mind like I never stopped using them, or like I've been programming in this language for 10 years.
Except when it comes to Classes. I added some classes to code that had previously just been functions, and you know what I did - or rather, forgot to do? Put in the 'self'. In front of some of the variable accesses, but more noticably, at the start of *every single method argument list.* This cannot be any longer blamed as a hangover from Java - I've written a ton more code, more recently in Python than in Java or any other OO language. What's more, every time I go back to Python after a break of more than about a week or so, I start making this 'mistake' again. The perennial justification for this 'feature' of the language? That old Python favourite, "Explicit is better than implicit."
I'm sorry, but EXPLICIT IS NOT NECESSARILY BETTER THAN IMPLICIT. Assembler is explicit FFS. Intuitive, clever, dependable, expected, well-designed *implicit* behaviour is one of the chief reasons why I use a high level language. Implicitly garbage collect old objects for me? Yes, please!
I was once bitten by a Python wart I felt was bad enough to raise and spend some effort advocating change for on comp.lang.python (never got around to doing a PEP; partly laziness, partly young and inexperienced enough to be intimidated at the thought. Still am, perhaps.)
The following doesn't work as any sane, reasonable person would expect:
# Blog code, not tested class A(): def __eq__(self, obj): return True a = A() b = [] assert a == b assert not (a != b)
The second assertion fails. Why? Because coding __eq__, the most obvious way to make a class have equality based comparisons, buys you nothing from the != operator. != isn't (by default) a synonym for the negation of == (unlike in, say, every other language ever); not only will Python let you make them mean different things, without documenting this fact - it actively encourages you to do so.
There were a disturbingly high number of people defending this (including one quite renowned Pythonista, think it might have been Effbot). Some had the temerity to fall back on "Explicit is better than implict: if you want != to work, you should damn well code __ne__!"
Why, for heaven's sake, should I have to, when in 99.99% of use cases (and of those 0.01% instances quoted in the argument at the time only one struck me as remotely compelling) every programmer is going to want __ne__ to be the logical negation of __eq__? Why, dear Python, are you making me write evil Java-style language power reducing boilerplate to do the thing you should be doing yourself anyway? What's more, every programmer is going to unconciously expect it to work this way, and be as utterly as mystified as me when it fails to do so. Don't tell me to RTFM and don't tell me to be explicit. I'll repeat myself - if I wanted to be explicit, I'd be using C and managing my own memory thank you very much. Better yet, I'd explicitly and graphically swear - swear in frustration at this entrenched design philosophy madness that afflicts my favourite language.
I think the real problem with the explicit is better than implicit, though, is that while you can see the underlying truth its trying to get at (which is perhaps better expressed by Ruby's more equivocal, less dependable, but more useful Principle of Least Surprise), in its stated form its actually kind of meanginless and is used mainly in defence of warts - no, we'll call them for what they are, a language design *bugs*.
You see, the problem is, there's no such thing of explict in programming. Its not a question of not doing things implicitly; its a question of doing the most sensible thing implicitly. For example this python code:
which in turn gives us self as a reference to some_obj, and Python's OO model merrily pretends its the same as Java's when in fact is a smarter version that just superficially looks the same.
The problem is that the explicit requirement to have self at the start of every method is something that should be shipped off to the implicit category. You should have to be explicit, yes - explicit when you want the *other* behaviour, of self *not* being an argument, because thats the more unusual, less likely case.
Likewise,
a != b
is implicitly equivalent to something like calling this function (may not be correct, its a while since I was heavily involved in this issue):
def equal(a, b): if hasattr(a, "__ne__"): return a.__ne__(b) if hasattr(b, "__ne__"): return b.__ne__(a) if hasattr(a, "__cmp__"): return not (a.__cmp__(b) == 0) if hasattr(b, "__cmp__"): return not (b.__cmp__(a) == 0) return not (a is b)
There's absolutely nothing explicit about this. I wasn't arguing for making behaviour implicit; I was arguing for changing the stupid implict behaviour to something more sensible and less surprising.
The sad thing is there are plenty of smart Python programmers who will justify all kinds of idiocy in the name of their holy crusade against the implict.
If there was one change I could make to Python, it would be to get that damn line out of the Zen.
> I'm a big Python fan who used to be involved semi regularly in > comp.lang.python (lots of lurking, occasional posting) but kind of > trailed off a bit. I just wrote a frustration inspired rant on my > blog, and I thought it was relevant enough as a wider issue to the > Python community to post here for your discussion and consideration.
> This is not flamebait. I love Python, and I'm not out to antagonise > the community. I also realise that one of the issues I raise is way > too ingrained to be changed now. I'd just like to share my thinking on > a misstep in Python's guiding principles that has done more harm than > good IMO. So anyway, here's the post.
> I've become utterly convinced that at least one criticism leveled at > my favourite overall programming language, Python, is utterly true and > fair. After quite a while away from writing Python code, I started > last night on a whim to knock up some code for a prototype of an idea > I once had. It's going swimmingly; the Python Image Library, which I'd > never used before, seems quick, intuitive, and with the all the > features I need for this project. As for Python itself, well, my heart > still belongs to whitespace delimitation. All the basics of Python > coding are there in my mind like I never stopped using them, or like > I've been programming in this language for 10 years.
> Except when it comes to Classes. I added some classes to code that had > previously just been functions, and you know what I did - or rather, > forgot to do? Put in the 'self'. In front of some of the variable > accesses, but more noticably, at the start of *every single method > argument list.* This cannot be any longer blamed as a hangover from > Java - I've written a ton more code, more recently in Python than in > Java or any other OO language. What's more, every time I go back to > Python after a break of more than about a week or so, I start making > this 'mistake' again. The perennial justification for this 'feature' > of the language? That old Python favourite, "Explicit is better than > implicit."
> I'm sorry, but EXPLICIT IS NOT NECESSARILY BETTER THAN IMPLICIT. > Assembler is explicit FFS. Intuitive, clever, dependable, expected, > well-designed *implicit* behaviour is one of the chief reasons why I > use a high level language. Implicitly garbage collect old objects for > me? Yes, please!
> I was once bitten by a Python wart I felt was bad enough to raise and > spend some effort advocating change for on comp.lang.python (never got > around to doing a PEP; partly laziness, partly young and inexperienced > enough to be intimidated at the thought. Still am, perhaps.)
> The following doesn't work as any sane, reasonable person would > expect:
> # Blog code, not tested > class A(): > def __eq__(self, obj): > return True > a = A() > b = [] > assert a == b > assert not (a != b)
> The second assertion fails. Why? Because coding __eq__, the most > obvious way to make a class have equality based comparisons, buys you > nothing from the != operator. != isn't (by default) a synonym for the > negation of == (unlike in, say, every other language ever); not only > will Python let you make them mean different things, without > documenting this fact - it actively encourages you to do so.
> There were a disturbingly high number of people defending this > (including one quite renowned Pythonista, think it might have been > Effbot). Some had the temerity to fall back on "Explicit is better > than implict: if you want != to work, you should damn well code > __ne__!"
> Why, for heaven's sake, should I have to, when in 99.99% of use cases > (and of those 0.01% instances quoted in the argument at the time only > one struck me as remotely compelling) every programmer is going to > want __ne__ to be the logical negation of __eq__? Why, dear Python, > are you making me write evil Java-style language power reducing > boilerplate to do the thing you should be doing yourself anyway? > What's more, every programmer is going to unconciously expect it to > work this way, and be as utterly as mystified as me when it fails to > do so. Don't tell me to RTFM and don't tell me to be explicit. I'll > repeat myself - if I wanted to be explicit, I'd be using C and > managing my own memory thank you very much. Better yet, I'd explicitly > and graphically swear - swear in frustration at this entrenched design > philosophy madness that afflicts my favourite language.
> I think the real problem with the explicit is better than implicit, > though, is that while you can see the underlying truth its trying to > get at (which is perhaps better expressed by Ruby's more equivocal, > less dependable, but more useful Principle of Least Surprise), in its > stated form its actually kind of meanginless and is used mainly in > defence of warts - no, we'll call them for what they are, a language > design *bugs*.
> You see, the problem is, there's no such thing of explict in > programming. Its not a question of not doing things implicitly; its a > question of doing the most sensible thing implicitly. For example this > python code:
> which in turn gives us self as a reference to some_obj, and Python's > OO model merrily pretends its the same as Java's when in fact is a > smarter version that just superficially looks the same.
> The problem is that the explicit requirement to have self at the start > of every method is something that should be shipped off to the > implicit category. You should have to be explicit, yes - explicit when > you want the *other* behaviour, of self *not* being an argument, > because thats the more unusual, less likely case.
> Likewise,
> a != b
> is implicitly equivalent to something like calling this function (may > not be correct, its a while since I was heavily involved in this > issue):
> def equal(a, b): > if hasattr(a, "__ne__"): return a.__ne__(b) > if hasattr(b, "__ne__"): return b.__ne__(a) > if hasattr(a, "__cmp__"): return not (a.__cmp__(b) == 0) > if hasattr(b, "__cmp__"): return not (b.__cmp__(a) == 0) > return not (a is b)
> There's absolutely nothing explicit about this. I wasn't arguing for > making behaviour implicit; I was arguing for changing the stupid > implict behaviour to something more sensible and less surprising.
> The sad thing is there are plenty of smart Python programmers who will > justify all kinds of idiocy in the name of their holy crusade against > the implict.
> If there was one change I could make to Python, it would be to get > that damn line out of the Zen.
P.S. Forgive the typos, it was blogged in extreme haste and then only quickly proofread and edited before posting here. Hopefully the point I'm making is not diminshed by your reduced respect for me as a result of my carelessness :-)
On Jul 24, 1:41 pm, Jordan <jordanrastr...@gmail.com> wrote:
> Hi everyone,
> I'm a big Python fan who used to be involved semi regularly in > comp.lang.python (lots of lurking, occasional posting) but kind of > trailed off a bit. I just wrote a frustration inspired rant on my > blog, and I thought it was relevant enough as a wider issue to the > Python community to post here for your discussion and consideration.
[...snip...]
+1 for most of your opinion. I was also bitten by the __eq__/__ne__ problem this morning. :)
Jordan wrote: > Except when it comes to Classes. I added some classes to code that had > previously just been functions, and you know what I did - or rather, > forgot to do? Put in the 'self'. In front of some of the variable > accesses, but more noticably, at the start of *every single method > argument list.* This cannot be any longer blamed as a hangover from > Java - I've written a ton more code, more recently in Python than in > Java or any other OO language. What's more, every time I go back to > Python after a break of more than about a week or so, I start making > this 'mistake' again. The perennial justification for this 'feature' > of the language? That old Python favourite, "Explicit is better than > implicit."
Do you seriously think that Python is designed by mindless application of a set of humorous and somewhat self-deprecating observations posted to a newsgroup a number of years ago?
I just think Explicit is better than Implicit is taken seriously by a large segment the Python community as a guiding principle, and overall its influence does more harm than good.
Clearly self being in every argument list was a decision arrived at long before the Zen was ever coined. Its merely an example of what I feel is a shortcoming in the conventional 'pythonic' approach to thinking about problems.
The reluctance to admit that the __eq__ behaviour is a poor design choice is further evidence; its something (unlike self) that quite conceivably could be changed, and should be changed, but its somehow seen (by certain people) as the way that Python should do things.
Please get your facts, the behaviour *is* actually fully documented:
""" There are no implied relationships among the comparison operators. The truth of x==y does not imply that x!=y is false. Accordingly, when defining __eq__(), one should also define __ne__() so that the operators will behave as expected. """ http://docs.python.org/ref/customization.html
FWIW, the __lt__ / __le__ / __eq__ / __ne__ / __gt__ / __ge__ methods set, known as "rich comparisons", was added in Python 2.1 to give more fine-grained control on comparisons. If you don't need such a granularity, just implement the __cmp__ method and you'll have all comparison operators working as expected.
2/ wrt/ self in functions signatures:
How would you handle this case with an implicit 'self' :
In message <52404933-ce08-4dc1-a558-935bbbae7...@r35g2000prm.googlegroups.com>, Jordan wrote:
> Except when it comes to Classes. I added some classes to code that had > previously just been functions, and you know what I did - or rather, > forgot to do? Put in the 'self'. In front of some of the variable > accesses, but more noticably, at the start of *every single method > argument list.*
The reason is quite simple. Python is not truly an "object-oriented" language. It's sufficiently close to fool those accustomed to OO ways of doing things, but it doesn't force you to do things that way. You still have the choice. An implicit "self" would take away that choice.
> # Blog code, not tested > class A(): > def __eq__(self, obj): > return True > a = A() > b = [] > assert a == b > assert not (a != b)
> The second assertion fails. Why? Because coding __eq__, the most > obvious way to make a class have equality based comparisons, buys you > nothing from the != operator. != isn't (by default) a synonym for the > negation of == (unlike in, say, every other language ever);
This is just plain wrong for at least C# and C++. C# wants you to explicitly overload "!=", if you have overloaded "==", C++ complains about "!=" not being defined for class A. If you had derived A from a another class in C++, the compiler would happily use the operator from the base class instead of doing silly aliasing of "!=" to "! ==" ...
> The sad thing is there are plenty of smart Python programmers who will > justify all kinds of idiocy in the name of their holy crusade against > the implict.
> If there was one change I could make to Python, it would be to get > that damn line out of the Zen.
Fortunately, Python isn't designed according to your ideas, and won't change, so consider your posting a waste of time. If feeling like bringing such old "issues" up again next time, spend your time learning another programming language, as you would obviously not get happy with Python anyway ...
-- Freedom is always the freedom of dissenters. (Rosa Luxemburg)
OK, it seems my original reply to Bruno got lost in the Aether (apologies therefore if a paraphrased "quantum duplicate" of this message is eventually forthcoming.)
Torsten has adequately responded to his second point, so I need only replicated what I said for the first.
> Please get your facts, the behaviour *is* actually fully documented:
I have the facts. I know full well the behaviour is documented - it was pointed out at the time of the original discussion. Documenting a confusing, unintuitive design decision (whether its in a programming language, an end user GUI app or anything in between) doesn't justify it.
To attack a strawman: "foolanguage uses the bar IO library; printing to stdout takes about 10 mins on the average machine. But thats ok, because look, its documented right here."
> FWIW, the __lt__ / __le__ / __eq__ / __ne__ / __gt__ / __ge__ methods > set, known as "rich comparisons", was added in Python 2.1 to give more > fine-grained control on comparisons. If you don't need such a > granularity, just implement the __cmp__ method and you'll have all > comparison operators working as expected.
First, the most serious justification for rich comparisons I remember seeing was that scipy "needed" them. I never saw a good reason scipy couldnt use methods like the rest of us mortals, nor why it was justifiable introducing a wart into the entire language for the sake of mildly conveniencing an (admittedly important and widely used) library.
Second, fine, have silly C++-operator-overloading-style rich comparisons that confuse people reading your code if you must. Why does it have to be the default behaviour? Its people wanting __ne__ do do something other than not __eq__ who should have to be explicit about it.
Third, __cmp__ is no good as a fix. Most classes that wan't equality comparison (== and !=) don't want ordered based comparison (>= etc.) thrown in as well. I shouldn't implement __cmp__ unless I want my class to implement every order comparison operator.
Fourth, I'm trying to examine the wider implications of the Explicit > Implict mantra here, not resurrect an old campaign to change != behaviour that I think is probably a lost cause (if it happens as a side effect though, that'd be kinda cool.)
> This is just plain wrong for at least C# and C++. C# wants you to > explicitly overload "!=", if you have overloaded "==",
While this is as inconvenient as Python at least it doesn't catch you unawares. C# 1 (or maybe 0.5), Python 0.
> C++ complains > about "!=" not being defined for class A.
See above. C++ 1, Python 0.
So in showing my clearly hyperbolic comment was technically incorrect (something I could have told you myself), you have merely shown that two languages I find vastly inferior to Python overall are actually better than it in this case.
> Fortunately, Python isn't designed according to your ideas, and won't > change, so consider your posting a waste of time. If feeling like bringing > such old "issues" up again next time, spend your time learning another > programming language, as you would obviously not get happy with Python > anyway ...
OK, if that's your response, that's sad. Of course, I try to learn new languages all the time. Python is still IMO the best. If the attitude in the community in response to feedback/criticism has gone from "maybe you've got a point" to "your a lunatic, we'll never change", well, only Python will suffer in the long term.
On Jul 24, 8:01 pm, Lawrence D'Oliveiro <l...@geek-
central.gen.new_zealand> wrote: > In message > <52404933-ce08-4dc1-a558-935bbbae7...@r35g2000prm.googlegroups.com>, Jordan > wrote:
> > Except when it comes to Classes. I added some classes to code that had > > previously just been functions, and you know what I did - or rather, > > forgot to do? Put in the 'self'. In front of some of the variable > > accesses, but more noticably, at the start of *every single method > > argument list.*
> The reason is quite simple. Python is not truly an "object-oriented" > language. It's sufficiently close to fool those accustomed to OO ways of > doing things, but it doesn't force you to do things that way. You still > have the choice. An implicit "self" would take away that choice.
You could still explicitly request non-implicit self on a method by method basis.
> > How would you handle this case with an implicit 'self' :
> > class Foo(object): > > pass
> > def bar(self): > > print self
> > Foo.bar = bar
> Just like this. However, the compiler could add "self" to > non-decorated methods which are defined within "class".
And $self2, $self3, ... to the object methods of nested classes and $cls2, $cls3, ... to the classmethods of those classes...?
And when we are at it, here is a nice little exercise for the proponents of compiler magic.
Write a decorator that takes and returns a method and prints the object the method is bound to. It's very easy to do it when the object is passed explicitely:
On Jul 24, 8:21 pm, Jordan <jordanrastr...@gmail.com> wrote:
> If the attitude > in the community in response to feedback/criticism has gone from > "maybe you've got a point" to "your a lunatic, we'll never change", > well, only Python will suffer in the long term.
Personally, I think it has more to do with statements like "there are plenty of smart Python programmers who will justify all kinds of idiocy in the name of their holy crusade" than with your position. You don't begin a discussion by discrediting anyone who might disagree with you as some kind of religious bigot while simultaneously holding that you are the only sane voice speaking.
>> Fortunately, Python isn't designed according to your ideas, and won't >> change, so consider your posting a waste of time. If feeling like >> bringing such old "issues" up again next time, spend your time learning >> another programming language, as you would obviously not get happy with >> Python anyway ...
> OK, if that's your response, that's sad. Of course, I try to learn new > languages all the time. Python is still IMO the best. If the attitude > in the community in response to feedback/criticism has gone from > "maybe you've got a point" to "your a lunatic, we'll never change", > well, only Python will suffer in the long term.
I don't really mind, what you think about my response. Python will suffer from it as little as it will suffer from your complaints: These things will not change, whatever any of us says about them. So this discussion unlikely to produce any new insight, especially because this as been discussed over and over again in the past, without any effect on Python.
Let's just drop this, and if you want to complain next time, just complain about something, that is really worth being complained about, like for instance old and outdated modules in the standard library, or real showstoppers in Python (e.g. the GIL).
-- Freedom is always the freedom of dissenters. (Rosa Luxemburg)
> Personally, I think it has more to do with statements like "there are > plenty of smart Python programmers who will > justify all kinds of idiocy in the name of their holy crusade" than > with your position. You don't begin a discussion by discrediting > anyone who might disagree with you as some kind of religious bigot > while simultaneously holding that you are the only sane voice > speaking.
I didn't set out to discredit anyone who might disagree with me; in fact I didn't in anyway try to pre-empt any person who might disagree with my thesis. I merely stated an observation - I have in the past seen seemingly intelligent people take silly stands in the name of Explicit is greater than Implicit (not just on comp.lang.python, and not just concerning != or self).
I wish in retrospect I'd had the time, patience and focus to edit the initial post to make it more measured and less inflammatory, because its clear the tone detracts from the argument I'm making, which I feel still stands.
So if you wish, ignore the specifics of the frustration that inspired me and consider only the thrust of what I'm saying:
"Explicit is better than Implict" considered harmful. Discuss.
Jordan <jordanrastr...@gmail.com> writes: > I just think Explicit is better than Implicit is taken seriously by > a large segment the Python community as a guiding principle
Indeed it is. However, it has to compete with all the other principles in the Zen of Python, which have equal status.
> and overall its influence does more harm than good.
Thanks for your opinion. I disagree strongly: I think its influence is nicely balanced by the other important principles that are also followed.
-- \ “The way to build large Python applications is to componentize | `\ and loosely-couple the hell out of everything.” —Aahz | _o__) | Ben Finney
Jordan <jordanrastr...@gmail.com> writes: > If the attitude in the community in response to feedback/criticism > has gone from "maybe you've got a point" to "your a lunatic, we'll > never change", well, only Python will suffer in the long term.
You're not a lunatic.
We, and Python itself, change quite readily.
Neither of those mean your ideas in this instance have merit.
-- \ “Pinky, are you pondering what I'm pondering?” “Well, I think | `\ so, Brain, but do I really need two tongues?” —_Pinky and The | _o__) Brain_ | Ben Finney
> I don't really mind, what you think about my response. Python will suffer > from it as little as it will suffer from your complaints: These things > will not change, whatever any of us says about them. So this discussion > unlikely to produce any new insight, especially because this as been > discussed over and over again in the past, without any effect on Python.
You're right, of course. Because Python is in so many ways what I'm looking for in a language, I transform it in my mind to my own, personal ideal, close to the real existing language but with what I consider to be the imperfections removed.
I'm not suggesting getting rid of explicit self, even in "Python 4000." Not because of the advantages it gives, which are some but don't outweigh the net loss in my ledger. It just wouldn't be Pythonic. I know its not a Pythonic thing to want. Thats my problem - because I have a largely Pythonic approach in some areas, it upsets me when there's a mismatch. So lets say I'm -1 for introducing it into a language and +0 for keeping it in Python now that its entrenched.
If a lot of users keep bringing up something like this, well my attitude used to be the same as yours - "learn to love Python for what it is." Maybe
> Let's just drop this, and if you want to complain next time, just complain > about something, that is really worth being complained about, like for > instance old and outdated modules in the standard library, or real > showstoppers in Python (e.g. the GIL).
Its worth complaining about because I'm not just someone who has stumbled across Python after years of Java and PHP, and hasn't really grokked it, and has jumped on the net at once to start a flamewar. I'm someone who loves Python, uses it in preference to other languages, and have now returned to it after a bit of a break and its finally hit me over the head like a tonne of bricks "Hey, I can see exactly what all those internet trolls were talking about. This *is* a really annoying and silly state of affairs."
I was trying not to change explicit self, or even != (which has a much better case.) I was trying to ask the community to reconsider a premise that the language is built around. Explicit is actually kinda annoying a lot of the time, viz., java. This is about social and philosophical adjustments, not technical ones.
In reality? I'll just keep writing Python (hopefully enough so that explicit self become burned into muscle memory), and use other languages when necessary (no more C than I have to, looking forward to dabbling in Erlang soon, and one day overcoming the parentheses phobia enough to really tackle Lisp properly). When I'm old enough and wise enough, and have the time, energy and inclination, maybe I'll sit down and put a proper effort into designing and implementing a new language that bests suits my own particular style and needs. Just maybe it'll be good enough that smart people will rally to defend its design principles from people attacking them on the internet :-)
> OK, it seems my original reply to Bruno got lost in the Aether > (apologies therefore if a paraphrased "quantum duplicate" of this > message is eventually forthcoming.)
> Torsten has adequately responded to his second point,
Not MHO, by far.
> so I need only > replicated what I said for the first.
>> Please get your facts, the behaviour *is* actually fully documented:
> I have the facts. I know full well the behaviour is documented
Then why do you write, let me quote:
""" (snip) coding __eq__ (snip) buys you nothing from the != operator. != isn't (by default) a synonym for the negation of == (unlike in, say, every other language ever); not only will Python let you make them mean different things, without documenting this fact - it actively encourages you to do so. """
>- it > was pointed out at the time of the original discussion. Documenting a > confusing, unintuitive design decision (whether its in a programming > language, an end user GUI app or anything in between) doesn't justify > it.
I was not commenting on the actual design choice, just stating that it is actually documented.
> To attack a strawman: "foolanguage uses the bar IO library; printing > to stdout takes about 10 mins on the average machine. But thats ok, > because look, its documented right here."
And you're talking about strawman ??? Come on, you obviously can tell the difference between a one-line statement and your above strawman argument, don't you ?
Please understand that I'm not arguing about this particular design choice (and FWIW, I'd mostly agree on the point that having a != b different from not (a == b) is actually a wart). I'm just correcting your statement about the behaviour of __eq__ / __ne__ not being documented, which is obviously false.
>> How would you handle this case with an implicit 'self' :
>> class Foo(object): >> pass
>> def bar(self): >> print self
>> Foo.bar = bar
> Just like this. However, the compiler could add "self" to > non-decorated methods which are defined within "class".
What's defined within classes are plain functions. It's actually the lookup mechanism that wraps them into methods (and manage to insert the current instance as first argument).
> Please understand that I'm not arguing about this particular design > choice (and FWIW, I'd mostly agree on the point that having a != b > different from not (a == b) is actually a wart). I'm just correcting > your statement about the behaviour of __eq__ / __ne__ not being > documented, which is obviously false.
> (snip)
What was the reasoning behind having both __eq__ / __ne__ anyway? To fit in with the equality comparisons? I do agree this one seems like a wart, but not a serious one. I'd say it would make more sense for the interpreter to provide a warning on classes that define one and not that other, at least if set to a certain level, similar to -3 for depreciated.
(Or does this exist? I think a "wart" catching level that outputs potential warts and issues would be a useful addition!)
> """ > (snip) coding __eq__ (snip) buys you > nothing from the != operator. != isn't (by default) a synonym for the > negation of == (unlike in, say, every other language ever); not only > will Python let you make them mean different things, without > documenting this fact - it actively encourages you to do so. > """
My words aren't as clear as they should be. I mean that Python lets *you* do something without documenting, or rather stating to use a better term, that your intention is the non-obvious one. I'm not saying that Python itself lacks documentation for its own behaviour; I'm saying it should force you to make your intentions clear and visible to someone reading your code when you want to do something non- obvious.
> I was not commenting on the actual design choice, just stating that it > is actually documented.
Yes, it is. I apologise for the poor construction of my statement which led to this confusion.
> And you're talking about strawman ??? Come on, you obviously can tell > the difference between a one-line statement and your above strawman > argument, don't you ?
I'm talking about strawmen because I was deliberately choosing to invoke one with rhetorical flourish for the purposes of making my point forcefully. I wanted people to be clear that I knew perfectly well what I was doing and that they needn't call me out on it.
> Please understand that I'm not arguing about this particular design > choice (and FWIW, I'd mostly agree on the point that having a != b > different from not (a == b) is actually a wart). I'm just correcting > your statement about the behaviour of __eq__ / __ne__ not being > documented, which is obviously false.
Good, at least we've come to a point in this discussion where I can firmly agree with somebody.
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