Tieche Bruce A MSgt USMTM/AFD wrote:
> I am new to python,
>
> Could someone explain (in English) how and when to use self?
>
> I have been reading, and haven't found a good example/explanation
>
>
> Bruce Tieche ([EMAIL PROTECTED])
Hi, Sometimes it's hard to get a simple answer to programming questions
as everyone sees different parts of the elephant. ;-)
The use of self is needed because methods in class's are shared between
all the instances (objects created from class's). Because of this
sharing, each method in a class needs a name to receive the specific
instance reference which called it.
If every instance had it's own copy of all the methods in a class, we
might not need 'self', but our programs would become extreme memory
hogs. So sharing code is the great benefit of class's.
For example...
class myclass(object):
def foo(self, a, b):
self.c = a + b
The method foo is defined but not executed until it is called later from
an instance. It's located in the class, but may be called from a lot,
(thousands or more), different instances made from this class.
bar = myclass() # create a single instance (object)
# and bind it to the name bar.
Then when you do...
bar.foo(1,2) # converted to -> myclass(bar, 1, 2)
It calls the 'foo' method located in the parent class and pass's a
reference to 'bar' as the first argument. 'self' becomes the new name
for bar within foo.
self.c = a + b # same as -> bar.c = a + b
This should be enough to visualize the basic relationship. Hope it helped.
Cheers,
Ron
--
http://mail.python.org/mailman/listinfo/python-list
