Some problems with classes
Why/how is it possible to add variables like this? I don't understand this mechanism: http://docs.python.org/tut/node11.html#SECTION001133 class Employee: pass john = Employee() # Create an empty employee record # Fill the fields of the record john.name = 'John Doe' john.dept = 'computer lab' john.salary = 1000 --- Also, I can't get multiple inheritance to work. Don't mind that the a vegan obviously don't inherit from an animal and a vegetable. I didn't come up with anything better, it is just to learn about inheritance. class Animal(object): def __init__(self, name, weight): self.name = name self.weight = weight def speak(self): print "speak" class Vegetable(object): def __init__(self, name, volume): self.name = name self.volume = volume def split(self): print "tjoff" class Vegan(Animal, Vegetable): #pass def __init__(self, name, attacks): self.name = name self.attacks = attacks >>> Traceback (most recent call last): File "C:/Python25/Progs//Movie.py", line 42, in class ActionComedy(Movie, ActionMovie): TypeError: Error when calling the metaclass bases Cannot create a consistent method resolution order (MRO) for bases Movie, ActionMovie >>> also, when inheriting, can I inherit __init__() somehow? If I want the same attributes but perhaps some additional methods for example. -- http://mail.python.org/mailman/listinfo/python-list
Re: Some problems with classes
On Sun, Aug 31, 2008 at 6:39 PM, ssecorp <[EMAIL PROTECTED]> wrote: > Why/how is it possible to add variables like this? I don't understand > this mechanism: > http://docs.python.org/tut/node11.html#SECTION001133 Under the covers, Python objects are implemented using dictionaries, so adding an attribute just adds a new key-value pair to the object's internal dictionary (which, incidentally, you can access as someobj.__dict__). > > class Employee: >pass > > john = Employee() # Create an empty employee record > > # Fill the fields of the record > john.name = 'John Doe' > john.dept = 'computer lab' > john.salary = 1000 > > --- > > Also, I can't get multiple inheritance to work. > > Don't mind that the a vegan obviously don't inherit from an animal and > a vegetable. I didn't come up with anything better, it is just to > learn about inheritance. > > > class Animal(object): >def __init__(self, name, weight): >self.name = name >self.weight = weight > >def speak(self): >print "speak" > > class Vegetable(object): >def __init__(self, name, volume): >self.name = name >self.volume = volume > >def split(self): >print "tjoff" > > class Vegan(Animal, Vegetable): >#pass >def __init__(self, name, attacks): >self.name = name >self.attacks = attacks > > > Traceback (most recent call last): > File "C:/Python25/Progs//Movie.py", line 42, in >class ActionComedy(Movie, ActionMovie): > TypeError: Error when calling the metaclass bases >Cannot create a consistent method resolution > order (MRO) for bases Movie, ActionMovie The class names in error message here don't match the classes you declared above. Give us the actual code you're using or at least a stub version. > > > also, when inheriting, can I inherit __init__() somehow? If I want the > same attributes but perhaps some additional methods for example. Use super() to call your superclasses' __init__() methods. See super()'s entry in http://docs.python.org/lib/built-in-funcs.html for more info. - Chris > > -- > http://mail.python.org/mailman/listinfo/python-list > -- Follow the path of the Iguana... http://rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Some problems with classes
class Animal(object): def __init__(self, name, weight): self.name = name self.weight = weight def speak(self): print "speak" class Vegetable(object): def __init__(self, name, volume): self.name = name self.volume = volume def split(self): print "tjoff" class Vegan(Animal, Vegetable): def __init__(self, name, attacks): self.name = name self.attacks = attacks -- http://mail.python.org/mailman/listinfo/python-list
Re: Some problems with classes
also, how does super() work more exactly? I can't get it quite to work. class Movie(object): def __init__(self, movieId, grades, date): self.movieId = movieId self.grades = grades self.date = date def newGrade(self, grade): self.grades.append(grade) def spam(self): print "inherits all the way down?" def averageGrade(self): return sum(grade for grade in self.grades) / \ len(self.grades) class ActionMovie(Movie): super(Movie) ##def __init__(self, movieId, grades, date, kills): ##self.movieId = movieId ##self.grades = grades ##self.date = date ##self.kills = kills def newGrade(self, grade, date): self.grades.append(grade) self.date = date def prd(self): print self.date class Comedy(ActionMovie): def __init__(self, movieId, grades, date): self.movieId = movieId self.grades = grades self.date = date def donk(self): print "im a donkey!" subclasses has to be indented? class C(B): def meth(self, arg): super(C, self).meth(arg) -- http://mail.python.org/mailman/listinfo/python-list
Re: Some problems with classes
It works when I inherit from 2 classes but not when I inherit from 2 subclasses. - from __future__ import division class Movie(object): def __init__(self, movieId, grades, date): self.movieId = movieId self.grades = grades self.date = date def newGrade(self, grade): self.grades.append(grade) def spam(self): print "inherits all the way down?" def averageGrade(self): return sum(grade for grade in self.grades) / \ len(self.grades) class ActionMovie(Movie): #super(Movie, self) def __init__(self, movieId, grades, date, kills): self.movieId = movieId self.grades = grades self.date = date self.kills = kills def newGrade(self, grade, date): self.grades.append(grade) self.date = date def prd(self): print self.date class Comedy(ActionMovie): def __init__(self, movieId, grades, date): self.movieId = movieId self.grades = grades self.date = date def donk(self): print "im a donkey!" ##class ActionComedy(Movie, ActionMovie): ##def __init__(self, movieId, grades, date): ##self.movieId = movieId ##self.grades = grades ##self.date = date class Animal(object): def __init__(self, name, weight): self.name = name self.weight = weight def speak(self): print "speak" class Vegetable(object): def __init__(self, name, volume): self.name = name self.volume = volume def split(self): print "tjoff" class Vegan(Animal, Vegetable): #pass #super() def __init__(self, name, attacks): self.name = name self.attacks = attacks -- http://mail.python.org/mailman/listinfo/python-list
Re: Some problems with classes
On Sep 1, 3:39 am, ssecorp <[EMAIL PROTECTED]> wrote: > > Traceback (most recent call last): > File "C:/Python25/Progs//Movie.py", line 42, in > class ActionComedy(Movie, ActionMovie): > TypeError: Error when calling the metaclass bases > Cannot create a consistent method resolution > order (MRO) for bases Movie, ActionMovie The MRO is explained here: http://www.python.org/download/releases/2.3/mro/ Super is explained here: http://www.artima.com/weblogs/index.jsp?blogger=micheles Be warned that those are not readings for a beginner, but if you want to use multiple inheritance and super you must be prepared ;) -- http://mail.python.org/mailman/listinfo/python-list
Re: Some problems with classes
Chris Rebert a écrit : On Sun, Aug 31, 2008 at 6:39 PM, ssecorp <[EMAIL PROTECTED]> wrote: Why/how is it possible to add variables like this? I don't understand this mechanism: http://docs.python.org/tut/node11.html#SECTION001133 Under the covers, Python objects are implemented using dictionaries, Not necessarily. so adding an attribute just adds a new key-value pair to the object's internal dictionary (which, incidentally, you can access as someobj.__dict__). Idem. -- http://mail.python.org/mailman/listinfo/python-list
