Re: [Tutor] OOD - Another class question
James Reynolds wrote: I have another question related to OOD. What I have is a module with one parent class and two child classes. Some stuff is done to the object that is passed to the function in one of the child classes and this then calls a function from the global class passing local variables (from the child class). When I do this, I am told: AttributeError: 'HillBuilder' object has no attribute 'MountainBuilder' The question is, what am I doing wrong? Here is an example: class MountainBuilder(object): def __init__(self, mountain): self.mountain = mountain self.mountain_func self.pinetree_func def pinetree_func(self, knoll) do stuff to knoll return knoll def mountain_func(self, hill) knoll = hill * 2 pinetree = pintree_func(knoll) return hill class HillBuilder(MountainBuilder): def __init__(self, mountain): OptionLoad.__init__(self, mountain) self.MountainBuilder.mountain_func self.hill_func def hill_func(self) hill= do stuff to self.mountain grassyknoll = MountainBuilder.mountain_func(hill) return grassy knoll do stuff with grassy knoll ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor The line grassyknoll = MountainBuilder.mountain ... Since you inherit MountainBuilder you call the mountain_func (which is a method :-) ) with self: grassyknoll = self.mountain_func(hill) All methods inside the MountainBuilder can be called as if they are a part of the HillBuilder (thus inheritance). Cheers, T ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] OOD - Another class question
"James Reynolds" wrote parent class and two child classes. Some stuff is done to the object that is passed to the function in one of the child classes and this then calls a function from the global class passing local variables (from the child class). You really need to tighten up on the terminology because the imprecision is part of your problems understanding the concepts. You pass an object to a method of a child class which calls a method in the parent class. You pass instance variables of the child class as arguments to the parent class method.. When I do this, I am told: AttributeError: 'HillBuilder' object has no attribute 'MountainBuilder' The question is, what am I doing wrong? Confusing inheritance with composition. Your child class does not have an attribute MountainBuilder, it *is* a MountainBuilder. self within the method referes to your subclass of MountainBuilder so you only need self. class MountainBuilder(object): def pinetree_func(self, knoll) do stuff to knoll return knoll def mountain_func(self, hill) knoll = hill * 2 pinetree = pintree_func(knoll) return hill class HillBuilder(MountainBuilder): def __init__(self, mountain): OptionLoad.__init__(self, mountain) self.MountainBuilder.mountain_func This should be self.mountain_func(mountain) def hill_func(self) hill= do stuff to self.mountain grassyknoll = MountainBuilder.mountain_func(hill) And this should be grassyknoll = self.mountain_func(hill) mountain func as a method of MountainBuilder is also a method of HillBuilder (thats what inheritance means) so you access it through self. Take a look at the BankAccount example in the OOP topic of my tutor for more examples of subclasses calling superclass methods HTH, -- Alan Gauld Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] OOD - Another class question
On Sun, Feb 28, 2010 at 06:24:09PM -0500, James Reynolds wrote: > I have another question related to OOD. What I have is a module with one > parent class and two child classes. Some stuff is done to the object that is > passed to the function in one of the child classes and this then calls a > function from the global class passing local variables (from the child > class). I think you're confusing containers with inheritance. > class MountainBuilder(object): > def __init__(self, mountain): > self.mountain = mountain > self.mountain_func <--- what's this? >self.pinetree_func <--- what's this? > > class HillBuilder(MountainBuilder): > def __init__(self, mountain): > OptionLoad.__init__(self, mountain) > self.MountainBuilder.mountain_func There is no MountainBuilder attribute in HillBuilder. Rather, HillBuilder is a refined type of a MountainBuilder, and inherits everything MountainBuilders have, plus what you change or add to that base in HillBuilder. You're treating it like it's a separate class which contains a MountainBuilder object inside it as an attribute. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] OOD - Another class question
I have another question related to OOD. What I have is a module with one parent class and two child classes. Some stuff is done to the object that is passed to the function in one of the child classes and this then calls a function from the global class passing local variables (from the child class). When I do this, I am told: AttributeError: 'HillBuilder' object has no attribute 'MountainBuilder' The question is, what am I doing wrong? Here is an example: class MountainBuilder(object): def __init__(self, mountain): self.mountain = mountain self.mountain_func self.pinetree_func def pinetree_func(self, knoll) do stuff to knoll return knoll def mountain_func(self, hill) knoll = hill * 2 pinetree = pintree_func(knoll) return hill class HillBuilder(MountainBuilder): def __init__(self, mountain): OptionLoad.__init__(self, mountain) self.MountainBuilder.mountain_func self.hill_func def hill_func(self) hill= do stuff to self.mountain grassyknoll = MountainBuilder.mountain_func(hill) return grassy knoll do stuff with grassy knoll ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
