"Khalid Al-Ghamdi" <emailkg...@gmail.com> wrote
class Robot:
population = 0
def __init__(self, name):
self.name=name
print ('initializing {0}'.format(self.name))
Robot.population+=1
def __del__(self):
'''I'm dying'''
print ('{0} is being destroyed!'.format(self.name))
Robot.population-=1
droid1 = Robot('D23')
1- In the class definition above, I don't get the "self.name=name". I
understand that the self is supposed to refer to the actual object, but
since it is an initialization method, there is no way to enter a name in
place of the arguments.
When you instantiate a class you create a new object and initialise it.
The way you do that in code is
object = ClassName(arguments)
What then happens is that the ClassName object is created
and its __init__ method is called with arguments passed to it.
So in your case when you do
droid1 = Robot("D23")
you are NOT assigning the class to droid1 you are creating
a new instance of Robot and passing the argument "D23" to
the init method as its name parameter. The __init__ method
then assigns the name to self.name, ie to droid1.name
The __xxx___ methods are all special methods that Python
calls indirectly. __del__ is called when an object is deleted so
is the complement of __init__. __eq__ is called when we do an equality
test:
if drioid1 == droid2
for example will actually call doid1.__eq__(droid2)
These methods allow us to change how operatrors work for our classes.
You might find it useful to read the OOP topic in my tutorial as
an secondary source to the book/course you are currently reading.
HTH,
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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