Programming Forums - Classes question

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Classes question

I'm having a bit of trouble figuring out classes. Here's a rough example of what I'm trying to do:

class Item_Class:
def __int__(self):
self.Name
self.Description
self.Price

List[]
List.append(Item_Class)
List[0].Name = "Something"
List[0].Description = "Something"
List[0].Price = "Something"

That works fine. But if I append the class to the list a second time, and assign some values to it, the previous instance of the class is changed to those values also.
What am I doing wrong? Isn't the idea of classes to be able to make different instances of it?

thanks

You need to change "List.append(Item_Class)" to "List.append(Item_Class())". The () initiates a new object for that class. You were appending to the list the direct reference to the class.

The following is a working example...

Note that the class's contents are completely blank. This is because you're declaring and initiating the variables externally. There is no need to put anything inside.

class Item_Class:

    pass



List = []



List.append(Item_Class())



List[0].Name = "IDLE"

List[0].Description = "Python Interpreter"

List[0].Price = 0.00





List.append(Item_Class())



List[1].Name = "My Help"

List[1].Description = "Programming Help From Sane"

List[1].Price = 0.00





print List[0].Name

print List[0].Description

print List[0].Price



print List[1].Name

print List[1].Description

print List[1].Price

However, if you want to write it in a way that provides a better understanding of how classes work, then consider the following...

class Item_Class:

    def __init__(self, Name, Description, Price):

        self.Name = Name

        self.Description = Description

        self.Price = Price



List = []



List.append(Item_Class("IDLE", "Python Interpreter", 0.00))

List.append(Item_Class("My Help", "Programming Help From Sane", 0.00))



print List[0].Name

print List[0].Description

print List[0].Price



print List[1].Name

print List[1].Description

print List[1].Price

Furthermore expanding on the program, we can get the same output like so...

class Item_Class:

    def __init__(self, Name, Description, Price):

        self.Name = Name

        self.Description = Description

        self.Price = Price



    def Output(self):

        print self.Name

        print self.Description

        print self.Price



List = []



List.append(Item_Class("IDLE", "Python Interpreter", 0.00))

List.append(Item_Class("My Help", "Programming Help From Sane", 0.00))



List[0].Output()

List[1].Output()

If anything I'm doing confuses you, don't hesitate to ask any questions. I also strongly suggest that you use the search to look through the Python forum for more examples using classes. I believe there's some excellent information provided by Arevos lying around.

I also urge you to use [code][/code] tags next time you post code.

Ahh, that makes sense. Thank you very much for simple and clear example.
On a related note were can I find out more about the different ways classes are used in programming?

BTW sorry about not puting the code in tags, I was going to but forgot because I was doing a couple things at the same time(maybe I should cut down on the Dr.pepper).

thanks again

The way classes are used in programming are for you to discover and apply yourself as a programmer. The applications of Object-Oriented programming are very vast, and can be applied basically anywhere. But the more you use it as a programmer, the more you'll see where it should and should not be applied.

Otherwise, I hope wherever you're learning classes from explains the general applications of classes, and where and where not to use them.