In Python, a class comes with member functions (methods), class variables, attributes/instance variables (and probably class methods too):
class Employee:
# Class Variable
company = "mycompany.com"
def __init__(self, first_name, last_name, position):
# Instance Variables
self._first_name = first_name
self._last_name = last_name
self._position = position
# Member function
def get_full_name(self):
return f"{self._first_name} {self._last_name}"
By creating an instance of the object
my_employee = Employee("John", "Wood", "Software Engineer")
we essentially trigger __init__ that is going to initialise the instance variables of the newly created Employee. This means that _first_name, _last_name and _position are explicit parameters of the specific my_employee instance.
Likewise, member functions return information or change the state of a specific instance.
Now any variable defined outside the constructor __init__ are considered to be class variables. Those variables are shared amongst all the instances of the class.
john = Employee("John", "Wood", "Software Engineer")
bob = Employee("Bob", "Smith", "DevOps Engineer0")
print(john.get_full_name())
print(bob.get_full_name())
print(john.company)
print(bob.company)
>>> John Wood
>>> Bob Smith
>>> mycompany.com
>>> mycompany.com
You can also use class methods in order to change the class variable for all the instances of the class. For example:
@classmethod
def change_my_companys_name(cls, name):
cls.company = name
and now change_my_companys_name()
bob.change_my_companys_name("mynewcompany.com")
will have effect on all the instances of class Employee:
print(bob.company)
print(john.company)
>>> mynewcompany.com
>>> mynewcompany.com