__init__ function arguments

[CoderMan]

Hello,

I am trying to make an __init__ function's argument be the previous argument of that function divided by 2.

class item: def __init__(self,value1,value2): self.v1 = value1 self.v2 = value2 x = item(10,item.v1/2)

However, when I run it I get the message that "type object 'item' has no attribute v1".

Any other ways to do it?

[Larz60+]

the statement:

x = item(10,item.v1/2)

is outside of the class, so cannot see v1 or v2

this script is not worthy of a class, but:
better to use inside of a function like:

class item: def __init__(self,value1,value2): self.v1 = value1 self.v2 = value2 def testit(): myitem = item(45, 78) ... # some time later x = item(10, myitem.v1/2) if __name__ == '__main__': testit()

[snippsat]

Maybe a little confusing to instantiate both myitem and x Larz60+,as it not clear that both is needed.

Here the basic.

class Item: def __init__(self, value1, value2): self.v1 = value1 self.v2 = value2

Use class:

>>> # Instantiate the Item object >>> x = Item(8, 4) >>> # Access the instance attributes >>> x.v1 8 >>> x.v2 4 >>> # At this point you can what you want instance attributes >>> x.v1 + x.v2 / 2 10.0 >>> x.v1 + x.v2 * 20 / x.v1 18.0

[CoderMan]

the statement:

x = item(10,item.v1/2)

is outside of the class, so cannot see v1 or v2

this script is not worthy of a class, but:
better to use inside of a function like:

class item: def __init__(self,value1,value2): self.v1 = value1 self.v2 = value2 def testit(): myitem = item(45, 78) ... # some time later x = item(10, myitem.v1/2) if __name__ == '__main__': testit()

Larz60+ thank you so much, but I just realized I made a mistake in the example!! I meant

x = item(10, x.v1/2)

So sorry for this, I really appreciate the reply from both you and snippsat!

[stullis]

You cannot reference x.v1 as an argument to the __init__() method because x doesn't exist yet. The class and its attributes aren't instantiated until after the __init__() method has completed. Until then, the attributes cannot be accessed.