PYTHON

class variable in python

# Class variables refer to variables that are made within a class.
# It is generated when you define the class.
# It's shared with all the instance of that class.
# Example:

class some_variable_holder(object):
    
    var = "This variable is created inside the class some_variable_holder()."
    
    def somefunc(self):
        print("Random function ran.")

thing = some_variable_holder()
another_thing = some_variable_holder()

# Both does the same thing because the same variable has been passed on from the class.
thing.var
another_thing.var

python class variable

class Foo:
    num_of_foos = 0     # class variable, shared by all instances
    raise_amt = 1.04    # class variable
    def __init__(self, x):
        self.instance_var = x
        Foo.num_of_foos += 1    # class safe way to use class variable
    def raise_me(self):
        # self.raise_amt allows object / subclass to override class variable
        return self.instance_var * self.raise_amt   

bar = Foo(1)
baz = Foo(1)
Foo.num_of_foos     # 2
bar.num_of_foos     # 2
bar.raise_me()      # 1.04
bar.raise_amt = 1.5 # create instance variable that overrides class variable
bar.raise_me()      # 1.5

python class variables

// no need to define variables explicitly like in java or c++
// we need to define them in __init__ method that creates, this i8s the key 
// __init__ basically it's constructor
// instance variables for the current object self( which denotes your created instance)
class A:
 def __init__(self,d):
     self.d=d
//above automaticaaly creates an instance variable d for you class object
hence 

ob=A(4)
// creates object ob with 1 instance variable d initialised to 4 

ALSO NOTE:
// in python there is no distinction between pointer variable and 
// normal variable we use same syntax for both unlike c++
// so how python distinguishes b/w a reference and normal var?
// by seeing what is being assigned to it on RHS