"tanner barnes" <tanner...@hotmail.com> wrote
I have a program with 2 classes and in one 4 variables
are created (their name, height, weight, and grade).
What im trying to make happen is to get the variables
from the first class and use them in the second class.
In general thats not a good idea. Each class should
manage its own data and you should pass objects
between objects. So first check that whatever your
second class wants to do with the data from your first
class can't be done by the first class itself via a method.
If you really do need to access the data there are
several approaches:
1) Direct access via the object
class C:
def __init__(s):
s.x = 42
class D:
def f(s, c):
s.y = c.x # direct access to a C instance
2) Access via a getter method returning each variable:
class C:
def __init__(s):
s.x = 42
def getX(s):
return s.x
class D:
def f(s, c):
s.y = c.getX() # access via a getter method
3) Access via a logical operation that returns all public data
class C:
def __init__(s):
s.x = 42
s.y = 66
def getData(s):
return (s.x, s.y)
class D:
def f(s, c):
s.x, s.y = c.getData() # access via a logical access method
My personal preference in Python is (1) for occasional single
value access (akin to a friend function in C++) or (3) for more
regular access requests.
But most of all I try to avoid cross class data access wherever possible.
As Peter Coad put it "Objects should do it to themselves...."
Otherwise known as the Law of Demeter.
HTH,
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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