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From "Mike Tutkowski (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (CLOUDSTACK-9373) Marvin issue with class and instance methods named the same
Date Tue, 17 May 2016 13:26:13 GMT

     [ https://issues.apache.org/jira/browse/CLOUDSTACK-9373?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mike Tutkowski resolved CLOUDSTACK-9373.
----------------------------------------
    Resolution: Fixed

> Marvin issue with class and instance methods named the same
> -----------------------------------------------------------
>
>                 Key: CLOUDSTACK-9373
>                 URL: https://issues.apache.org/jira/browse/CLOUDSTACK-9373
>             Project: CloudStack
>          Issue Type: Bug
>      Security Level: Public(Anyone can view this level - this is the default.) 
>          Components: marvin
>    Affects Versions: 4.9.0
>         Environment: N/A
>            Reporter: Mike Tutkowski
>            Assignee: Mike Tutkowski
>             Fix For: 4.9.0
>
>
> We have some methods in base.py that are named the same.
> Per my findings below, Python methods in a class should not be named the same even if one is a class method and the other is an instance method.
> The solution discussed on dev@ is to remove the instance versions (reason listed below).
> From a chain of e-mails on dev@:
> Python Question (with regards to Marvin)
> Mark as unread
> Tutkowski, Mike
> Sun 5/1/2016 7:16 PM
> Sent Items; Inbox
> "A bunch of UI scripts use those class methods (I didn't see us trying to use the instance methods anywhere)."
> I meant that a bunch of test scripts use those methods (not UI scripts).
> REPLYREPLY ALLFORWARD
> Mark as unread
> Tutkowski, Mike
> Sun 5/1/2016 5:24 PM
> Sent Items; Inbox
> To:
> dev@cloudstack.apache.org;
> So, the problem exists with both enableMaintenance and cancelMaintenance for hosts and with enableMaintenance for storage (not with cancelMaintenance for storage).
> A bunch of UI scripts use those class methods (I didn't see us trying to use the instance methods anywhere).
> I believe those class methods exist because the test scripts already have the UUIDs of the host or storage and those class methods provide a faster means of performing the action in question (when compared to having to retrieve a host or storage object from the applicable UUID and then invoke the method on it).
> That being the case, I think we should just keep the class methods.
> ________________________________________
> From: Will Stevens <williamstevens@gmail.com>
> Sent: Sunday, May 1, 2016 12:15 PM
> To: dev@cloudstack.apache.org
> Subject: Re: Python Question (with regards to Marvin)
> Ya. Let's see how prevalent the class method is to start with and we will
> cross that bridge after.
> On May 1, 2016 2:07 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com> wrote:
> > I was just "concerned" that those who have their own Marvin tests that are
> > not checked in might be broken if I don't keep the class method.
> > ________________________________________
> > From: Will Stevens <williamstevens@gmail.com>
> > Sent: Sunday, May 1, 2016 12:03 PM
> > To: dev@cloudstack.apache.org
> > Subject: Re: Python Question (with regards to Marvin)
> >
> > It will be easy to grep if there class methods, so we should start there.
> > If not, then I agree that an instance method is probably the best way to
> > go.
> > On May 1, 2016 12:41 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> > wrote:
> >
> > > However, from a design standpoint, I prefer the instance method here as
> > it
> > > would be nice to ask the object itself to place itself in maintenance
> > mode.
> > >
> > > So, it's really a question of just staying backward compatible (the class
> > > method) or a possibly better design (the instance method).
> > > ________________________________________
> > > From: Tutkowski, Mike <Mike.Tutkowski@netapp.com>
> > > Sent: Sunday, May 1, 2016 10:18 AM
> > > To: dev@cloudstack.apache.org
> > > Subject: Re: Python Question (with regards to Marvin)
> > >
> > > The question then becomes, do we want to keep the instance or the class
> > > method?
> > >
> > > There exists the same problem for at least one other pair of methods.
> > >
> > > Since the class method is listed second in the file currently, it is the
> > > only one of the two that can be utilized. That being the case, we might
> > > just want to keep the class method and remove the instance method.
> > >
> > > > On May 1, 2016, at 5:43 AM, Will Stevens <williamstevens@gmail.com>
> > > wrote:
> > > >
> > > > Yep. Looking like there is a bug in that file. Thanks for testing. :)
> > > >> On May 1, 2016 1:40 AM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> > > wrote:
> > > >>
> > > >> Here are my tests (run from http://ideone.com/).
> > > >>
> > > >> The short story is that having multiple methods with the same name
> > (even
> > > >> if one is an instance method and one is a class method) should
> > probably
> > > not
> > > >> be done.
> > > >>
> > > >> If you try to invoke the instance method (ex. test.run()), the last
> > > method
> > > >> by that name in the source file is invoked (which could be the class
> > > >> method). If the number of parameters don't match, that's an error.
> > > >>
> > > >> If you try to invoke the class method (ex. Test.run()), the last
> > method
> > > by
> > > >> that name in the source file is invoked. If this is not a class method
> > > or
> > > >> if the number of parameters don't match, that's an error.
> > > >>
> > > >> class Test:
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >>    def run(self):
> > > >>        print "instance hi"
> > > >>
> > > >> test = Test()
> > > >>
> > > >> test.run()
> > > >>
> > > >> What gets printed:
> > > >> instance hi
> > > >>
> > > >> class Test:
> > > >>    def run(self):
> > > >>        print "instance hi"
> > > >>
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >> test = Test()
> > > >>
> > > >> test.run()
> > > >>
> > > >> What gets printed:
> > > >> class hi
> > > >>
> > > >> class Test:
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >>    def run(self):
> > > >>        print "instance hi"
> > > >>
> > > >> # test = Test()
> > > >>
> > > >> Test.run()
> > > >>
> > > >> Runtime error
> > > >>
> > > >> class Test:
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >> # test = Test()
> > > >>
> > > >> Test.run()
> > > >>
> > > >> What gets printed:
> > > >> class hi
> > > >>
> > > >> class Test:
> > > >>    def run(self):
> > > >>        print "instance hi"
> > > >>
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >> # test = Test()
> > > >>
> > > >> Test.run()
> > > >>
> > > >> What gets printed:
> > > >> class hi
> > > >>
> > > >> class Test:
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >> # test = Test()
> > > >>
> > > >> Test.run()
> > > >>
> > > >> What gets printed:
> > > >> class hi
> > > >> ________________________________________
> > > >> From: Tutkowski, Mike
> > > >> Sent: Saturday, April 30, 2016 6:58 PM
> > > >> To: dev@cloudstack.apache.org
> > > >> Subject: Re: Python Question (with regards to Marvin)
> > > >>
> > > >> I can play around with it later tonight. I'm not home at the moment.
> > > >>
> > > >> When I did invoke it as Test.run(), it invoked the class method (the
> > > class
> > > >> method was listed after the instance method for that test, so I wasn't
> > > >> surprised that the class method did, in fact, get executed there).
> > > >>
> > > >> What I did not try was to list the class method first, then list the
> > > >> instance method, and then try to invoke the class method.
> > > >>
> > > >> As mentioned in my prior e-mail, when I did try to invoke the instance
> > > >> version of run, it was only successful if the instance version was the
> > > >> second one declared in the file. If the class method was declared
> > > second,
> > > >> then it was invoked even when I was trying to invoke the instance one.
> > > >>
> > > >>>> On Apr 30, 2016, at 6:06 PM, Will Stevens <williamstevens@gmail.com
> > >
> > > >>> wrote:
> > > >>>
> > > >>> That's strange. That means the @classmethod decorator is not working.
> > > You
> > > >>> should have gotten the instance method in both cases.
> > > >>>
> > > >>> What if you don't instantiate Test and only do the following.
> > > >>>
> > > >>> Test.run()
> > > >>>
> > > >>> In both cases.
> > > >>> On Apr 30, 2016 6:04 PM, "Tutkowski, Mike" <
> > Mike.Tutkowski@netapp.com>
> > > >>> wrote:
> > > >>>
> > > >>>> I ran this with an online Python tool and it calls the class method:
> > > >>>>
> > > >>>> 1       class Test:
> > > >>>> 2         def run(self):
> > > >>>> 3             print 'instance hi'
> > > >>>> 4
> > > >>>> 5         @classmethod
> > > >>>> 6         def run(cls):
> > > >>>> 7             print 'class hi'
> > > >>>> 8
> > > >>>> 9       test = Test()
> > > >>>> 10
> > > >>>> 11      test.run()
> > > >>>>
> > > >>>> If I reverse the order of the methods, the instance method is
> > invoked:
> > > >>>>
> > > >>>> 1       class Test:
> > > >>>> 2         @classmethod
> > > >>>> 3         def run(cls):
> > > >>>> 4             print 'class hi'
> > > >>>> 5
> > > >>>> 6         def run(self):
> > > >>>> 7             print 'instance hi'
> > > >>>> 8
> > > >>>> 9       test = Test()
> > > >>>> 10
> > > >>>> 11      test.run()
> > > >>>>
> > > >>>> As I suspected, I think this means we have a problem in base.py.
> > > >>>> ________________________________________
> > > >>>> From: Will Stevens <williamstevens@gmail.com>
> > > >>>> Sent: Saturday, April 30, 2016 1:46 PM
> > > >>>> To: dev@cloudstack.apache.org
> > > >>>> Subject: Re: Python Question (with regards to Marvin)
> > > >>>>
> > > >>>> I am on my phone so I have not been able to research this for you. I
> > > >> think
> > > >>>> you are right for the most part.  Instead of multiple methods,
> > python
> > > >> kind
> > > >>>> of fakes overloading by being to have named function arguments which
> > > can
> > > >>>> have default values, so you can call the method with a dynamic
> > number
> > > of
> > > >>>> arguments making it appear like you are overloading, but you are
> > > >> actually
> > > >>>> calling the same function.
> > > >>>>
> > > >>>> I think in this case the two methods are actually in different
> > scopes
> > > >> (even
> > > >>>> though they are next to each other).  The decorator actually wraps
> > the
> > > >>>> method, so I believe in the actual runtime the to methods are in
> > > >> different
> > > >>>> scopes.
> > > >>>>
> > > >>>> I would have to look into this more to know for sure. I am taking a
> > > few
> > > >>>> minute break from building garden boxes right now. :)
> > > >>>> On Apr 30, 2016 3:31 PM, "Tutkowski, Mike" <
> > Mike.Tutkowski@netapp.com
> > > >
> Mark as unread
> Will Stevens <williamstevens@gmail.com>
> Sun 5/1/2016 12:15 PM
> Inbox
> Ya. Let's see how prevalent the class method is to start with and we will
> cross that bridge after.
> On May 1, 2016 2:07 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com> wrote:
> > I was just "concerned" that those who have their own Marvin tests that are
> > not checked in might be broken if I don't keep the class method.
> > ________________________________________
> > From: Will Stevens <williamstevens@gmail.com>
> > Sent: Sunday, May 1, 2016 12:03 PM
> > To: dev@cloudstack.apache.org
> > Subject: Re: Python Question (with regards to Marvin)
> >
> > It will be easy to grep if there class methods, so we should start there.
> > If not, then I agree that an instance method is probably the best way to
> > go.
> > On May 1, 2016 12:41 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> > wrote:
> >
> > > However, from a design standpoint, I prefer the instance method here as
> > it
> > > would be nice to ask the object itself to place itself in maintenance
> > mode.
> > >
> > > So, it's really a question of just staying backward compatible (the class
> > > method) or a possibly better design (the instance method).
> > > ________________________________________
> > > From: Tutkowski, Mike <Mike.Tutkowski@netapp.com>
> > > Sent: Sunday, May 1, 2016 10:18 AM
> > > To: dev@cloudstack.apache.org
> > > Subject: Re: Python Question (with regards to Marvin)
> > >
> > > The question then becomes, do we want to keep the instance or the class
> > > method?
> > >
> > > There exists the same problem for at least one other pair of methods.
> > >
> > > Since the class method is listed second in the file currently, it is the
> > > only one of the two that can be utilized. That being the case, we might
> > > just want to keep the class method and remove the instance method.
> > >
> > > > On May 1, 2016, at 5:43 AM, Will Stevens <williamstevens@gmail.com>
> > > wrote:
> > > >
> > > > Yep. Looking like there is a bug in that file. Thanks for testing. :)
> > > >> On May 1, 2016 1:40 AM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> > > wrote:
> > > >>
> > > >> Here are my tests (run from http://ideone.com/).
> > > >>
> > > >> The short story is that having multiple methods with the same name
> > (even
> > > >> if one is an instance method and one is a class method) should
> > probably
> > > not
> > > >> be done.
> > > >>
> > > >> If you try to invoke the instance method (ex. test.run()), the last
> > > method
> > > >> by that name in the source file is invoked (which could be the class
> > > >> method). If the number of parameters don't match, that's an error.
> > > >>
> > > >> If you try to invoke the class method (ex. Test.run()), the last
> > method
> > > by
> > > >> that name in the source file is invoked. If this is not a class method
> > > or
> > > >> if the number of parameters don't match, that's an error.
> > > >>
> > > >> class Test:
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >>    def run(self):
> > > >>        print "instance hi"
> > > >>
> > > >> test = Test()
> > > >>
> > > >> test.run()
> > > >>
> > > >> What gets printed:
> > > >> instance hi
> > > >>
> > > >> class Test:
> > > >>    def run(self):
> > > >>        print "instance hi"
> > > >>
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >> test = Test()
> > > >>
> > > >> test.run()
> > > >>
> > > >> What gets printed:
> > > >> class hi
> > > >>
> > > >> class Test:
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >>    def run(self):
> > > >>        print "instance hi"
> > > >>
> > > >> # test = Test()
> > > >>
> > > >> Test.run()
> > > >>
> > > >> Runtime error
> > > >>
> > > >> class Test:
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >> # test = Test()
> > > >>
> > > >> Test.run()
> > > >>
> > > >> What gets printed:
> > > >> class hi
> > > >>
> > > >> class Test:
> > > >>    def run(self):
> > > >>        print "instance hi"
> > > >>
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >> # test = Test()
> > > >>
> > > >> Test.run()
> > > >>
> > > >> What gets printed:
> > > >> class hi
> > > >>
> > > >> class Test:
> > > >>    @classmethod
> > > >>    def run(cls):
> > > >>        print "class hi"
> > > >>
> > > >> # test = Test()
> > > >>
> > > >> Test.run()
> > > >>
> > > >> What gets printed:
> > > >> class hi
> > > >> ________________________________________
> > > >> From: Tutkowski, Mike
> > > >> Sent: Saturday, April 30, 2016 6:58 PM
> > > >> To: dev@cloudstack.apache.org
> > > >> Subject: Re: Python Question (with regards to Marvin)
> > > >>
> > > >> I can play around with it later tonight. I'm not home at the moment.
> > > >>
> > > >> When I did invoke it as Test.run(), it invoked the class method (the
> > > class
> > > >> method was listed after the instance method for that test, so I wasn't
> > > >> surprised that the class method did, in fact, get executed there).
> > > >>
> > > >> What I did not try was to list the class method first, then list the
> > > >> instance method, and then try to invoke the class method.
> > > >>
> > > >> As mentioned in my prior e-mail, when I did try to invoke the instance
> > > >> version of run, it was only successful if the instance version was the
> > > >> second one declared in the file. If the class method was declared
> > > second,
> > > >> then it was invoked even when I was trying to invoke the instance one.
> > > >>
> > > >>>> On Apr 30, 2016, at 6:06 PM, Will Stevens <williamstevens@gmail.com
> > >
> > > >>> wrote:
> > > >>>
> > > >>> That's strange. That means the @classmethod decorator is not working.
> > > You
> > > >>> should have gotten the instance method in both cases.
> > > >>>
> > > >>> What if you don't instantiate Test and only do the following.
> > > >>>
> > > >>> Test.run()
> > > >>>
> > > >>> In both cases.
> > > >>> On Apr 30, 2016 6:04 PM, "Tutkowski, Mike" <
> > Mike.Tutkowski@netapp.com>
> > > >>> wrote:
> > > >>>
> > > >>>> I ran this with an online Python tool and it calls the class method:
> > > >>>>
> > > >>>> 1       class Test:
> > > >>>> 2         def run(self):
> > > >>>> 3             print 'instance hi'
> > > >>>> 4
> > > >>>> 5         @classmethod
> > > >>>> 6         def run(cls):
> > > >>>> 7             print 'class hi'
> > > >>>> 8
> > > >>>> 9       test = Test()
> > > >>>> 10
> > > >>>> 11      test.run()
> > > >>>>
> > > >>>> If I reverse the order of the methods, the instance method is
> > invoked:
> > > >>>>
> > > >>>> 1       class Test:
> > > >>>> 2         @classmethod
> > > >>>> 3         def run(cls):
> > > >>>> 4             print 'class hi'
> > > >>>> 5
> > > >>>> 6         def run(self):
> > > >>>> 7             print 'instance hi'
> > > >>>> 8
> > > >>>> 9       test = Test()
> > > >>>> 10
> > > >>>> 11      test.run()
> > > >>>>
> > > >>>> As I suspected, I think this means we have a problem in base.py.
> > > >>>> ________________________________________
> > > >>>> From: Will Stevens <williamstevens@gmail.com>
> > > >>>> Sent: Saturday, April 30, 2016 1:46 PM
> > > >>>> To: dev@cloudstack.apache.org
> > > >>>> Subject: Re: Python Question (with regards to Marvin)
> > > >>>>
> > > >>>> I am on my phone so I have not been able to research this for you. I
> > > >> think
> > > >>>> you are right for the most part.  Instead of multiple methods,
> > python
> > > >> kind
> > > >>>> of fakes overloading by being to have named function arguments which
> > > can
> > > >>>> have default values, so you can call the method with a dynamic
> > number
> > > of
> > > >>>> arguments making it appear like you are overloading, but you are
> > > >> actually
> > > >>>> calling the same function.
> > > >>>>
> > > >>>> I think in this case the two methods are actually in different
> > scopes
> > > >> (even
> > > >>>> though they are next to each other).  The decorator actually wraps
> > the
> > > >>>> method, so I believe in the actual runtime the to methods are in
> > > >> different
> > > >>>> scopes.
> > > >>>>
> > > >>>> I would have to look into this more to know for sure. I am taking a
> > > few
> > > >>>> minute break from building garden boxes right now. :)
> > > >>>> On Apr 30, 2016 3:31 PM, "Tutkowski, Mike" <
> > Mike.Tutkowski@netapp.com
> > > >
> Mark as unread
> Tutkowski, Mike
> Sun 5/1/2016 12:06 PM
> Sent Items; Inbox
> I was just "concerned" that those who have their own Marvin tests that are not checked in might be broken if I don't keep the class method.
> ________________________________________
> From: Will Stevens <williamstevens@gmail.com>
> Sent: Sunday, May 1, 2016 12:03 PM
> To: dev@cloudstack.apache.org
> Subject: Re: Python Question (with regards to Marvin)
> It will be easy to grep if there class methods, so we should start there.
> If not, then I agree that an instance method is probably the best way to
> go.
> On May 1, 2016 12:41 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> wrote:
> > However, from a design standpoint, I prefer the instance method here as it
> > would be nice to ask the object itself to place itself in maintenance mode.
> >
> > So, it's really a question of just staying backward compatible (the class
> > method) or a possibly better design (the instance method).
> > ________________________________________
> > From: Tutkowski, Mike <Mike.Tutkowski@netapp.com>
> > Sent: Sunday, May 1, 2016 10:18 AM
> > To: dev@cloudstack.apache.org
> > Subject: Re: Python Question (with regards to Marvin)
> >
> > The question then becomes, do we want to keep the instance or the class
> > method?
> >
> > There exists the same problem for at least one other pair of methods.
> >
> > Since the class method is listed second in the file currently, it is the
> > only one of the two that can be utilized. That being the case, we might
> > just want to keep the class method and remove the instance method.
> >
> > > On May 1, 2016, at 5:43 AM, Will Stevens <williamstevens@gmail.com>
> > wrote:
> > >
> > > Yep. Looking like there is a bug in that file. Thanks for testing. :)
> > >> On May 1, 2016 1:40 AM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> > wrote:
> > >>
> > >> Here are my tests (run from http://ideone.com/).
> > >>
> > >> The short story is that having multiple methods with the same name (even
> > >> if one is an instance method and one is a class method) should probably
> > not
> > >> be done.
> > >>
> > >> If you try to invoke the instance method (ex. test.run()), the last
> > method
> > >> by that name in the source file is invoked (which could be the class
> > >> method). If the number of parameters don't match, that's an error.
> > >>
> > >> If you try to invoke the class method (ex. Test.run()), the last method
> > by
> > >> that name in the source file is invoked. If this is not a class method
> > or
> > >> if the number of parameters don't match, that's an error.
> > >>
> > >> class Test:
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >>    def run(self):
> > >>        print "instance hi"
> > >>
> > >> test = Test()
> > >>
> > >> test.run()
> > >>
> > >> What gets printed:
> > >> instance hi
> > >>
> > >> class Test:
> > >>    def run(self):
> > >>        print "instance hi"
> > >>
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >> test = Test()
> > >>
> > >> test.run()
> > >>
> > >> What gets printed:
> > >> class hi
> > >>
> > >> class Test:
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >>    def run(self):
> > >>        print "instance hi"
> > >>
> > >> # test = Test()
> > >>
> > >> Test.run()
> > >>
> > >> Runtime error
> > >>
> > >> class Test:
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >> # test = Test()
> > >>
> > >> Test.run()
> > >>
> > >> What gets printed:
> > >> class hi
> > >>
> > >> class Test:
> > >>    def run(self):
> > >>        print "instance hi"
> > >>
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >> # test = Test()
> > >>
> > >> Test.run()
> > >>
> > >> What gets printed:
> > >> class hi
> > >>
> > >> class Test:
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >> # test = Test()
> > >>
> > >> Test.run()
> > >>
> > >> What gets printed:
> > >> class hi
> > >> ________________________________________
> > >> From: Tutkowski, Mike
> > >> Sent: Saturday, April 30, 2016 6:58 PM
> > >> To: dev@cloudstack.apache.org
> > >> Subject: Re: Python Question (with regards to Marvin)
> > >>
> > >> I can play around with it later tonight. I'm not home at the moment.
> > >>
> > >> When I did invoke it as Test.run(), it invoked the class method (the
> > class
> > >> method was listed after the instance method for that test, so I wasn't
> > >> surprised that the class method did, in fact, get executed there).
> > >>
> > >> What I did not try was to list the class method first, then list the
> > >> instance method, and then try to invoke the class method.
> > >>
> > >> As mentioned in my prior e-mail, when I did try to invoke the instance
> > >> version of run, it was only successful if the instance version was the
> > >> second one declared in the file. If the class method was declared
> > second,
> > >> then it was invoked even when I was trying to invoke the instance one.
> > >>
> > >>>> On Apr 30, 2016, at 6:06 PM, Will Stevens <williamstevens@gmail.com>
> > >>> wrote:
> > >>>
> > >>> That's strange. That means the @classmethod decorator is not working.
> > You
> > >>> should have gotten the instance method in both cases.
> > >>>
> > >>> What if you don't instantiate Test and only do the following.
> > >>>
> > >>> Test.run()
> > >>>
> > >>> In both cases.
> > >>> On Apr 30, 2016 6:04 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> > >>> wrote:
> > >>>
> > >>>> I ran this with an online Python tool and it calls the class method:
> > >>>>
> > >>>> 1       class Test:
> > >>>> 2         def run(self):
> > >>>> 3             print 'instance hi'
> > >>>> 4
> > >>>> 5         @classmethod
> > >>>> 6         def run(cls):
> > >>>> 7             print 'class hi'
> > >>>> 8
> > >>>> 9       test = Test()
> > >>>> 10
> > >>>> 11      test.run()
> > >>>>
> > >>>> If I reverse the order of the methods, the instance method is invoked:
> > >>>>
> > >>>> 1       class Test:
> > >>>> 2         @classmethod
> > >>>> 3         def run(cls):
> > >>>> 4             print 'class hi'
> > >>>> 5
> > >>>> 6         def run(self):
> > >>>> 7             print 'instance hi'
> > >>>> 8
> > >>>> 9       test = Test()
> > >>>> 10
> > >>>> 11      test.run()
> > >>>>
> > >>>> As I suspected, I think this means we have a problem in base.py.
> > >>>> ________________________________________
> > >>>> From: Will Stevens <williamstevens@gmail.com>
> > >>>> Sent: Saturday, April 30, 2016 1:46 PM
> > >>>> To: dev@cloudstack.apache.org
> > >>>> Subject: Re: Python Question (with regards to Marvin)
> > >>>>
> > >>>> I am on my phone so I have not been able to research this for you. I
> > >> think
> > >>>> you are right for the most part.  Instead of multiple methods, python
> > >> kind
> > >>>> of fakes overloading by being to have named function arguments which
> > can
> > >>>> have default values, so you can call the method with a dynamic number
> > of
> > >>>> arguments making it appear like you are overloading, but you are
> > >> actually
> > >>>> calling the same function.
> > >>>>
> > >>>> I think in this case the two methods are actually in different scopes
> > >> (even
> > >>>> though they are next to each other).  The decorator actually wraps the
> > >>>> method, so I believe in the actual runtime the to methods are in
> > >> different
> > >>>> scopes.
> > >>>>
> > >>>> I would have to look into this more to know for sure. I am taking a
> > few
> > >>>> minute break from building garden boxes right now. :)
> > >>>> On Apr 30, 2016 3:31 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com
> > >
> > >>>> wrote:
> > >>>>
> > >>>>> Will - You can override a method in Python, but can you overload it?
> > >>
> > http://stackoverflow.com/questions/10202938/how-do-i-use-method-overloading-in-python
> > >>>>>
> > >>>>>>> On Apr 30, 2016, at 6:23 AM, Will Stevens <
> > williamstevens@gmail.com>
> > >>>>>> wrote:
> > >>>>>>
> > >>>>>> Here is a pretty good explanation.
> > >>
> > http://stackoverflow.com/questions/136097/what-is-the-difference-between-staticmethod-and-classmethod-in-python
> > >>>>>>
> > >>>>>> I am guessing that both exist because the function is called both
> > with
> > >>>> a
> > >>>>>> host instance and with the class itself.
> > >>>>>>
> > >>>>>> Class instance example: `h.enableMaintenance(client)`
> > >>>>>>
> > >>>>>> Class example: `Host.enableMaintenance(client, 1)`
> > >>>>>>
> > >>>>>> In both cases the first parameter is implicitly `h` and `Host`
> > >>>>>> respectively.
> > >>>>>>
> > >>>>>> I am not sure why we need both (because I am not familiar with how
> > >> this
> > >>>>>> code is called), but method overloading is definitely valid in
> > python.
> > >>>>>>
> > >>>>>> On Apr 30, 2016 1:08 AM, "Tutkowski, Mike" <
> > Mike.Tutkowski@netapp.com
> > >>>
> Mark as unread
> Will Stevens <williamstevens@gmail.com>
> Sun 5/1/2016 12:04 PM
> Inbox
> It will be easy to grep if there class methods, so we should start there.
> If not, then I agree that an instance method is probably the best way to
> go.
> On May 1, 2016 12:41 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> wrote:
> > However, from a design standpoint, I prefer the instance method here as it
> > would be nice to ask the object itself to place itself in maintenance mode.
> >
> > So, it's really a question of just staying backward compatible (the class
> > method) or a possibly better design (the instance method).
> > ________________________________________
> > From: Tutkowski, Mike <Mike.Tutkowski@netapp.com>
> > Sent: Sunday, May 1, 2016 10:18 AM
> > To: dev@cloudstack.apache.org
> > Subject: Re: Python Question (with regards to Marvin)
> >
> > The question then becomes, do we want to keep the instance or the class
> > method?
> >
> > There exists the same problem for at least one other pair of methods.
> >
> > Since the class method is listed second in the file currently, it is the
> > only one of the two that can be utilized. That being the case, we might
> > just want to keep the class method and remove the instance method.
> >
> > > On May 1, 2016, at 5:43 AM, Will Stevens <williamstevens@gmail.com>
> > wrote:
> > >
> > > Yep. Looking like there is a bug in that file. Thanks for testing. :)
> > >> On May 1, 2016 1:40 AM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> > wrote:
> > >>
> > >> Here are my tests (run from http://ideone.com/).
> > >>
> > >> The short story is that having multiple methods with the same name (even
> > >> if one is an instance method and one is a class method) should probably
> > not
> > >> be done.
> > >>
> > >> If you try to invoke the instance method (ex. test.run()), the last
> > method
> > >> by that name in the source file is invoked (which could be the class
> > >> method). If the number of parameters don't match, that's an error.
> > >>
> > >> If you try to invoke the class method (ex. Test.run()), the last method
> > by
> > >> that name in the source file is invoked. If this is not a class method
> > or
> > >> if the number of parameters don't match, that's an error.
> > >>
> > >> class Test:
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >>    def run(self):
> > >>        print "instance hi"
> > >>
> > >> test = Test()
> > >>
> > >> test.run()
> > >>
> > >> What gets printed:
> > >> instance hi
> > >>
> > >> class Test:
> > >>    def run(self):
> > >>        print "instance hi"
> > >>
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >> test = Test()
> > >>
> > >> test.run()
> > >>
> > >> What gets printed:
> > >> class hi
> > >>
> > >> class Test:
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >>    def run(self):
> > >>        print "instance hi"
> > >>
> > >> # test = Test()
> > >>
> > >> Test.run()
> > >>
> > >> Runtime error
> > >>
> > >> class Test:
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >> # test = Test()
> > >>
> > >> Test.run()
> > >>
> > >> What gets printed:
> > >> class hi
> > >>
> > >> class Test:
> > >>    def run(self):
> > >>        print "instance hi"
> > >>
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >> # test = Test()
> > >>
> > >> Test.run()
> > >>
> > >> What gets printed:
> > >> class hi
> > >>
> > >> class Test:
> > >>    @classmethod
> > >>    def run(cls):
> > >>        print "class hi"
> > >>
> > >> # test = Test()
> > >>
> > >> Test.run()
> > >>
> > >> What gets printed:
> > >> class hi
> > >> ________________________________________
> > >> From: Tutkowski, Mike
> > >> Sent: Saturday, April 30, 2016 6:58 PM
> > >> To: dev@cloudstack.apache.org
> > >> Subject: Re: Python Question (with regards to Marvin)
> > >>
> > >> I can play around with it later tonight. I'm not home at the moment.
> > >>
> > >> When I did invoke it as Test.run(), it invoked the class method (the
> > class
> > >> method was listed after the instance method for that test, so I wasn't
> > >> surprised that the class method did, in fact, get executed there).
> > >>
> > >> What I did not try was to list the class method first, then list the
> > >> instance method, and then try to invoke the class method.
> > >>
> > >> As mentioned in my prior e-mail, when I did try to invoke the instance
> > >> version of run, it was only successful if the instance version was the
> > >> second one declared in the file. If the class method was declared
> > second,
> > >> then it was invoked even when I was trying to invoke the instance one.
> > >>
> > >>>> On Apr 30, 2016, at 6:06 PM, Will Stevens <williamstevens@gmail.com>
> > >>> wrote:
> > >>>
> > >>> That's strange. That means the @classmethod decorator is not working.
> > You
> > >>> should have gotten the instance method in both cases.
> > >>>
> > >>> What if you don't instantiate Test and only do the following.
> > >>>
> > >>> Test.run()
> > >>>
> > >>> In both cases.
> > >>> On Apr 30, 2016 6:04 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> > >>> wrote:
> > >>>
> > >>>> I ran this with an online Python tool and it calls the class method:
> > >>>>
> > >>>> 1       class Test:
> > >>>> 2         def run(self):
> > >>>> 3             print 'instance hi'
> > >>>> 4
> > >>>> 5         @classmethod
> > >>>> 6         def run(cls):
> > >>>> 7             print 'class hi'
> > >>>> 8
> > >>>> 9       test = Test()
> > >>>> 10
> > >>>> 11      test.run()
> > >>>>
> > >>>> If I reverse the order of the methods, the instance method is invoked:
> > >>>>
> > >>>> 1       class Test:
> > >>>> 2         @classmethod
> > >>>> 3         def run(cls):
> > >>>> 4             print 'class hi'
> > >>>> 5
> > >>>> 6         def run(self):
> > >>>> 7             print 'instance hi'
> > >>>> 8
> > >>>> 9       test = Test()
> > >>>> 10
> > >>>> 11      test.run()
> > >>>>
> > >>>> As I suspected, I think this means we have a problem in base.py.
> > >>>> ________________________________________
> > >>>> From: Will Stevens <williamstevens@gmail.com>
> > >>>> Sent: Saturday, April 30, 2016 1:46 PM
> > >>>> To: dev@cloudstack.apache.org
> > >>>> Subject: Re: Python Question (with regards to Marvin)
> > >>>>
> > >>>> I am on my phone so I have not been able to research this for you. I
> > >> think
> > >>>> you are right for the most part.  Instead of multiple methods, python
> > >> kind
> > >>>> of fakes overloading by being to have named function arguments which
> > can
> > >>>> have default values, so you can call the method with a dynamic number
> > of
> > >>>> arguments making it appear like you are overloading, but you are
> > >> actually
> > >>>> calling the same function.
> > >>>>
> > >>>> I think in this case the two methods are actually in different scopes
> > >> (even
> > >>>> though they are next to each other).  The decorator actually wraps the
> > >>>> method, so I believe in the actual runtime the to methods are in
> > >> different
> > >>>> scopes.
> > >>>>
> > >>>> I would have to look into this more to know for sure. I am taking a
> > few
> > >>>> minute break from building garden boxes right now. :)
> > >>>> On Apr 30, 2016 3:31 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com
> > >
> > >>>> wrote:
> > >>>>
> > >>>>> Will - You can override a method in Python, but can you overload it?
> > >>
> > http://stackoverflow.com/questions/10202938/how-do-i-use-method-overloading-in-python
> > >>>>>
> > >>>>>>> On Apr 30, 2016, at 6:23 AM, Will Stevens <
> > williamstevens@gmail.com>
> > >>>>>> wrote:
> > >>>>>>
> > >>>>>> Here is a pretty good explanation.
> > >>
> > http://stackoverflow.com/questions/136097/what-is-the-difference-between-staticmethod-and-classmethod-in-python
> > >>>>>>
> > >>>>>> I am guessing that both exist because the function is called both
> > with
> > >>>> a
> > >>>>>> host instance and with the class itself.
> > >>>>>>
> > >>>>>> Class instance example: `h.enableMaintenance(client)`
> > >>>>>>
> > >>>>>> Class example: `Host.enableMaintenance(client, 1)`
> > >>>>>>
> > >>>>>> In both cases the first parameter is implicitly `h` and `Host`
> > >>>>>> respectively.
> > >>>>>>
> > >>>>>> I am not sure why we need both (because I am not familiar with how
> > >> this
> > >>>>>> code is called), but method overloading is definitely valid in
> > python.
> > >>>>>>
> > >>>>>> On Apr 30, 2016 1:08 AM, "Tutkowski, Mike" <
> > Mike.Tutkowski@netapp.com
> > >>>
> Mark as unread
> Tutkowski, Mike
> Sun 5/1/2016 10:41 AM
> Sent Items; Inbox
> However, from a design standpoint, I prefer the instance method here as it would be nice to ask the object itself to place itself in maintenance mode.
> So, it's really a question of just staying backward compatible (the class method) or a possibly better design (the instance method).
> Mark as unread
> Tutkowski, Mike
> Sun 5/1/2016 10:18 AM
> Sent Items; Inbox
> The question then becomes, do we want to keep the instance or the class method?
> There exists the same problem for at least one other pair of methods.
> Since the class method is listed second in the file currently, it is the only one of the two that can be utilized. That being the case, we might just want to keep the class method and remove the instance method.
> > On May 1, 2016, at 5:43 AM, Will Stevens <williamstevens@gmail.com> wrote:
> > 
> > Yep. Looking like there is a bug in that file. Thanks for testing. :)
> Mark as unread
> Will Stevens <williamstevens@gmail.com>
> Sun 5/1/2016 5:43 AM
> Inbox
> Yep. Looking like there is a bug in that file. Thanks for testing. :)
> On May 1, 2016 1:40 AM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com> wrote:
> > Here are my tests (run from http://ideone.com/).
> >
> > The short story is that having multiple methods with the same name (even
> > if one is an instance method and one is a class method) should probably not
> > be done.
> >
> > If you try to invoke the instance method (ex. test.run()), the last method
> > by that name in the source file is invoked (which could be the class
> > method). If the number of parameters don't match, that's an error.
> >
> > If you try to invoke the class method (ex. Test.run()), the last method by
> > that name in the source file is invoked. If this is not a class method or
> > if the number of parameters don't match, that's an error.
> >
> > class Test:
> >     @classmethod
> >     def run(cls):
> >         print "class hi"
> >
> >     def run(self):
> >         print "instance hi"
> >
> > test = Test()
> >
> > test.run()
> >
> > What gets printed:
> > instance hi
> >
> > class Test:
> >     def run(self):
> >         print "instance hi"
> >
> >     @classmethod
> >     def run(cls):
> >         print "class hi"
> >
> > test = Test()
> >
> > test.run()
> >
> > What gets printed:
> > class hi
> >
> > class Test:
> >     @classmethod
> >     def run(cls):
> >         print "class hi"
> >
> >     def run(self):
> >         print "instance hi"
> >
> > # test = Test()
> >
> > Test.run()
> >
> > Runtime error
> >
> > class Test:
> >     @classmethod
> >     def run(cls):
> >         print "class hi"
> >
> > # test = Test()
> >
> > Test.run()
> >
> > What gets printed:
> > class hi
> >
> > class Test:
> >     def run(self):
> >         print "instance hi"
> >
> >     @classmethod
> >     def run(cls):
> >         print "class hi"
> >
> > # test = Test()
> >
> > Test.run()
> >
> > What gets printed:
> > class hi
> >
> > class Test:
> >     @classmethod
> >     def run(cls):
> >         print "class hi"
> >
> > # test = Test()
> >
> > Test.run()
> >
> > What gets printed:
> > class hi
> > ________________________________________
> > From: Tutkowski, Mike
> > Sent: Saturday, April 30, 2016 6:58 PM
> > To: dev@cloudstack.apache.org
> > Subject: Re: Python Question (with regards to Marvin)
> >
> > I can play around with it later tonight. I'm not home at the moment.
> >
> > When I did invoke it as Test.run(), it invoked the class method (the class
> > method was listed after the instance method for that test, so I wasn't
> > surprised that the class method did, in fact, get executed there).
> >
> > What I did not try was to list the class method first, then list the
> > instance method, and then try to invoke the class method.
> >
> > As mentioned in my prior e-mail, when I did try to invoke the instance
> > version of run, it was only successful if the instance version was the
> > second one declared in the file. If the class method was declared second,
> > then it was invoked even when I was trying to invoke the instance one.
> >
> > > On Apr 30, 2016, at 6:06 PM, Will Stevens <williamstevens@gmail.com>
> Mark as unread
> Tutkowski, Mike
> Sat 4/30/2016 11:40 PM
> Sent Items; Inbox
> >> Here are my tests (run from http://ideone.com/).
> >>
> >> The short story is that having multiple methods with the same name (even
> >> if one is an instance method and one is a class method) should probably not
> >> be done.
> >>
> >> If you try to invoke the instance method (ex. test.run()), the last method
> >> by that name in the source file is invoked (which could be the class
> >> method). If the number of parameters don't match, that's an error.
> >>
> >> If you try to invoke the class method (ex. Test.run()), the last method by
> >> that name in the source file is invoked. If this is not a class method or
> >> if the number of parameters don't match, that's an error.
> >>
> >> class Test:
> >>    @classmethod
> >>    def run(cls):
> >>        print "class hi"
> >>
> >>    def run(self):
> >>        print "instance hi"
> >>
> >> test = Test()
> >>
> >> test.run()
> >>
> >> What gets printed:
> >> instance hi
> >>
> >> class Test:
> >>    def run(self):
> >>        print "instance hi"
> >>
> >>    @classmethod
> >>    def run(cls):
> >>        print "class hi"
> >>
> >> test = Test()
> >>
> >> test.run()
> >>
> >> What gets printed:
> >> class hi
> >>
> >> class Test:
> >>    @classmethod
> >>    def run(cls):
> >>        print "class hi"
> >>
> >>    def run(self):
> >>        print "instance hi"
> >>
> >> # test = Test()
> >>
> >> Test.run()
> >>
> >> Runtime error
> >>
> >> class Test:
> >>    @classmethod
> >>    def run(cls):
> >>        print "class hi"
> >>
> >> # test = Test()
> >>
> >> Test.run()
> >>
> >> What gets printed:
> >> class hi
> >>
> >> class Test:
> >>    def run(self):
> >>        print "instance hi"
> >>
> >>    @classmethod
> >>    def run(cls):
> >>        print "class hi"
> >>
> >> # test = Test()
> >>
> >> Test.run()
> >>
> >> What gets printed:
> >> class hi
> >>
> >> class Test:
> >>    @classmethod
> >>    def run(cls):
> >>        print "class hi"
> >>
> >> # test = Test()
> >>
> >> Test.run()
> >>
> >> What gets printed:
> >> class hi
> Mark as unread
> Tutkowski, Mike
> Sat 4/30/2016 6:58 PM
> Sent Items; Inbox
> I can play around with it later tonight. I'm not home at the moment.
> When I did invoke it as Test.run(), it invoked the class method (the class method was listed after the instance method for that test, so I wasn't surprised that the class method did, in fact, get executed there).
> What I did not try was to list the class method first, then list the instance method, and then try to invoke the class method.
> As mentioned in my prior e-mail, when I did try to invoke the instance version of run, it was only successful if the instance version was the second one declared in the file. If the class method was declared second, then it was invoked even when I was trying to invoke the instance one.
> > On Apr 30, 2016, at 6:06 PM, Will Stevens <williamstevens@gmail.com> wrote:
> > 
> > That's strange. That means the @classmethod decorator is not working. You
> > should have gotten the instance method in both cases.
> > 
> > What if you don't instantiate Test and only do the following.
> > 
> > Test.run()
> > 
> > In both cases.
> Mark as unread
> Will Stevens <williamstevens@gmail.com>
> Sat 4/30/2016 6:06 PM
> Inbox
> That's strange. That means the @classmethod decorator is not working. You
> should have gotten the instance method in both cases.
> What if you don't instantiate Test and only do the following.
> Test.run()
> In both cases.
> On Apr 30, 2016 6:04 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> wrote:
> > I ran this with an online Python tool and it calls the class method:
> >
> > 1       class Test:
> > 2         def run(self):
> > 3             print 'instance hi'
> > 4
> > 5         @classmethod
> > 6         def run(cls):
> > 7             print 'class hi'
> > 8
> > 9       test = Test()
> > 10
> > 11      test.run()
> >
> > If I reverse the order of the methods, the instance method is invoked:
> >
> > 1       class Test:
> > 2         @classmethod
> > 3         def run(cls):
> > 4             print 'class hi'
> > 5
> > 6         def run(self):
> > 7             print 'instance hi'
> > 8
> > 9       test = Test()
> > 10
> > 11      test.run()
> >
> > As I suspected, I think this means we have a problem in base.py.
> Mark as unread
> Tutkowski, Mike
> Sat 4/30/2016 4:03 PM
> Sent Items; Inbox
> >> I ran this with an online Python tool and it calls the class method:
> >> 
> >> 1       class Test:
> >> 2         def run(self):
> >> 3             print 'instance hi'
> >> 4
> >> 5         @classmethod
> >> 6         def run(cls):
> >> 7             print 'class hi'
> >> 8
> >> 9       test = Test()
> >> 10
> >> 11      test.run()
> >> 
> >> If I reverse the order of the methods, the instance method is invoked:
> >> 
> >> 1       class Test:
> >> 2         @classmethod
> >> 3         def run(cls):
> >> 4             print 'class hi'
> >> 5
> >> 6         def run(self):
> >> 7             print 'instance hi'
> >> 8
> >> 9       test = Test()
> >> 10
> >> 11      test.run()
> >> 
> >> As I suspected, I think this means we have a problem in base.py.
> >> ________________________________________
> >> From: Will Stevens <williamstevens@gmail.com>
> >> Sent: Saturday, April 30, 2016 1:46 PM
> >> To: dev@cloudstack.apache.org
> >> Subject: Re: Python Question (with regards to Marvin)
> >> 
> >> I am on my phone so I have not been able to research this for you. I think
> >> you are right for the most part.  Instead of multiple methods, python kind
> >> of fakes overloading by being to have named function arguments which can
> >> have default values, so you can call the method with a dynamic number of
> >> arguments making it appear like you are overloading, but you are actually
> >> calling the same function.
> >> 
> >> I think in this case the two methods are actually in different scopes (even
> >> though they are next to each other).  The decorator actually wraps the
> >> method, so I believe in the actual runtime the to methods are in different
> >> scopes.
> >> 
> >> I would have to look into this more to know for sure. I am taking a few
> >> minute break from building garden boxes right now. :)
> Mark as unread
> Will Stevens <williamstevens@gmail.com>
> Sat 4/30/2016 1:46 PM
> Inbox
> I am on my phone so I have not been able to research this for you. I think
> you are right for the most part.  Instead of multiple methods, python kind
> of fakes overloading by being to have named function arguments which can
> have default values, so you can call the method with a dynamic number of
> arguments making it appear like you are overloading, but you are actually
> calling the same function.
> I think in this case the two methods are actually in different scopes (even
> though they are next to each other).  The decorator actually wraps the
> method, so I believe in the actual runtime the to methods are in different
> scopes.
> I would have to look into this more to know for sure. I am taking a few
> minute break from building garden boxes right now. :)
> On Apr 30, 2016 3:31 PM, "Tutkowski, Mike" <Mike.Tutkowski@netapp.com>
> wrote:
> > Will - You can override a method in Python, but can you overload it?
> >
> >
> > http://stackoverflow.com/questions/10202938/how-do-i-use-method-overloading-in-python
> >
> > > On Apr 30, 2016, at 6:23 AM, Will Stevens <williamstevens@gmail.com>
> Mark as unread
> Tutkowski, Mike
> Sat 4/30/2016 1:31 PM
> Sent Items; Inbox
> Will - You can override a method in Python, but can you overload it?
> http://stackoverflow.com/questions/10202938/how-do-i-use-method-overloading-in-python
> > On Apr 30, 2016, at 6:23 AM, Will Stevens <williamstevens@gmail.com> wrote:
> > 
> > Here is a pretty good explanation.
> > 
> > http://stackoverflow.com/questions/136097/what-is-the-difference-between-staticmethod-and-classmethod-in-python
> > 
> > I am guessing that both exist because the function is called both with a
> > host instance and with the class itself.
> > 
> > Class instance example: `h.enableMaintenance(client)`
> > 
> > Class example: `Host.enableMaintenance(client, 1)`
> > 
> > In both cases the first parameter is implicitly `h` and `Host`
> > respectively.
> > 
> > I am not sure why we need both (because I am not familiar with how this
> > code is called), but method overloading is definitely valid in python.
> Mark as unread
> Tutkowski, Mike
> Sat 4/30/2016 9:40 AM
> Sent Items; Inbox
> Allow me to clarify. :-)
> host.enableMaintenance(apiclient) is how I was invoking it. Just like a regular instance method.
> For some reason, it wanted to invoke the class method when I did that and was complaining about the lack of a parameter.
> That being the case, I switched my code to the following (to make use of the class method):
> Host.enableMaintenance(apiclient, host.id)
> The weird part is that it seems like Python was trying to invoke the class method when I had syntax specifying I wanted to invoke the instance method.
> To circumvent the issue, I just switched my syntax to make use of the class method instead of the instance method.
> Seems like I shouldn't have had to do that, though.
> > On Apr 30, 2016, at 6:30 AM, Will Stevens <williamstevens@gmail.com> wrote:
> > 
> > You are probably getting this error because you are trying to call:
> > Host.enableMaintenance(client)
> > 
> > Check my examples above for how to call it.
> > 
> > Sorry I am on my phone, so I am not very efficient with my phone and cant
> > civet you better details. :)
> >> On Apr 30, 2016 8:23 AM, "Will Stevens" <williamstevens@gmail.com> wrote:
> >> 
> >> Here is a pretty good explanation.
> >> 
> >> 
> >> http://stackoverflow.com/questions/136097/what-is-the-difference-between-staticmethod-and-classmethod-in-python
> >> 
> >> I am guessing that both exist because the function is called both with a
> >> host instance and with the class itself.
> >> 
> >> Class instance example: `h.enableMaintenance(client)`
> >> 
> >> Class example: `Host.enableMaintenance(client, 1)`
> >> 
> >> In both cases the first parameter is implicitly `h` and `Host`
> >> respectively.
> >> 
> >> I am not sure why we need both (because I am not familiar with how this
> >> code is called), but method overloading is definitely valid in python.
> Mark as unread
> Will Stevens <williamstevens@gmail.com>
> Sat 4/30/2016 6:30 AM
> Inbox
> You are probably getting this error because you are trying to call:
> Host.enableMaintenance(client)
> Check my examples above for how to call it.
> Sorry I am on my phone, so I am not very efficient with my phone and cant
> civet you better details. :)
> Mark as unread
> Will Stevens <williamstevens@gmail.com>
> Sat 4/30/2016 6:23 AM
> Inbox
> Here is a pretty good explanation.
> http://stackoverflow.com/questions/136097/what-is-the-difference-between-staticmethod-and-classmethod-in-python
> I am guessing that both exist because the function is called both with a
> host instance and with the class itself.
> Class instance example: `h.enableMaintenance(client)`
> Class example: `Host.enableMaintenance(client, 1)`
> In both cases the first parameter is implicitly `h` and `Host`
> respectively.
> I am not sure why we need both (because I am not familiar with how this
> code is called), but method overloading is definitely valid in python.
> Mark as unread
> Prashanth Manthena <prashanth.manthena@nuagenetworks.net>
> Sat 4/30/2016 6:10 AM
> Inbox
> Hi Mike,
> classmethod's first argument is always its class as it is always bound to
> the class, which is not the case with normal methods. Thus, both of the
> above methods can in essence still co-exist in base.py as they serve
> different purposes.
> In the latter classmethod, you need to pass your host object ID as one of
> the argument while calling it with its class name as its first argument.
> e.g. Host.enableMaintenance(self.apiclient, host_1.id)
> Note: "Host" is the class name of the above methods in base.py. "host_1" is
> your host object.
> In the former method, you just need to call it with your host object as its
> first argument, it takes the host ID from the passed host object.
> e.g. host_1.enableMaintenance(self.apiclient)
> Mark as unread
> Tutkowski, Mike <Mike.Tutkowski@netapp.com>
> Fri 4/29/2016 11:08 PM
> Inbox
> > Hi everyone,
> >
> >
> > I received an error when trying to invoke the instance version of
> > enableMaintenance (below).
> >
> >
> > 'TypeError: enableMaintenance() takes exactly 3 arguments (2 given)\n']
> >
> >
> > I looked at base.py and it has the following with regards to maintenance
> > mode for hosts:
> >
> >
> >     def enableMaintenance(self, apiclient):
> >
> >         """enables maintenance mode Host"""
> >
> >
> >         cmd = prepareHostForMaintenance.prepareHostForMaintenanceCmd()
> >
> >         cmd.id = self.id
> >
> >         return apiclient.prepareHostForMaintenance(cmd)
> >
> >
> >     @classmethod
> >
> >     def enableMaintenance(cls, apiclient, id):
> >
> >         """enables maintenance mode Host"""
> >
> >
> >         cmd = prepareHostForMaintenance.prepareHostForMaintenanceCmd()
> >
> >         cmd.id = id
> >
> >         return apiclient.prepareHostForMaintenance(cmd)
> >
> >
> > Now, I definitely have a lot more Java experience than Python, but - as
> > far as I know - having two methods with the same name such as this (even if
> > one is an instance method and the other is a class method) is not really
> > "permitted" in Python.
> >
> >
> > I mean, technically it's permitted, but the second one will override the
> > first one.
> >
> >
> > Can any of our Python people comment on this?
> >
> >
> > I was thinking I'd remove the class method (assuming my knowledge here
> > regarding this topic is correct).
> >
> >
> > Thanks!
> >
> > Mike
> Mark as unread
> Tutkowski, Mike
> Fri 4/29/2016 11:08 PM
> Hi everyone,
> I received an error when trying to invoke the instance version of enableMaintenance (below).
> 'TypeError: enableMaintenance() takes exactly 3 arguments (2 given)\n']
> I looked at base.py and it has the following with regards to maintenance mode for hosts:
>     def enableMaintenance(self, apiclient):
>         """enables maintenance mode Host"""
>         cmd = prepareHostForMaintenance.prepareHostForMaintenanceCmd()
>         cmd.id = self.id
>         return apiclient.prepareHostForMaintenance(cmd)
>     @classmethod
>     def enableMaintenance(cls, apiclient, id):
>         """enables maintenance mode Host"""
>         cmd = prepareHostForMaintenance.prepareHostForMaintenanceCmd()
>         cmd.id = id
>         return apiclient.prepareHostForMaintenance(cmd)
> Now, I definitely have a lot more Java experience than Python, but - as far as I know - having two methods with the same name such as this (even if one is an instance method and the other is a class method) is not really "permitted" in Python.
> I mean, technically it's permitted, but the second one will override the first one.
> Can any of our Python people comment on this?
> I was thinking I'd remove the class method (assuming my knowledge here regarding this topic is correct).
> Thanks!
> Mike



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