Issue
class Employee:
pay_raise_percent = 0
def __init__(self, name, salary):
self.name = name
self.salary = salary
p1 = Employee('John', 50_000)
p2 = Employee('Alex', 75_000)
p3 = Employee('Caleb', 90_000)
Employee.pay_raise_percent = 1.04
print(p1.salary, p2.salary, p3.salary, sep='\n')
# 52000 78000 93600
is it possible to make it so that changing a class attribute leads to an automatic increase in the salary of all instances by this value without doing that explicitly for each of them?
Solution
Sounds like an excellent use case for properties. Properties look like ordinary instance variables but act like methods. Consider
class Employee:
pay_raise_percent = 1.00
def __init__(self, name, salary):
self.name = name
self._salary = salary # "Private" variable
@property
def salary(self):
return self._salary * Employee.pay_raise_percent
p1 = Employee('John', 50_000)
print(p1.salary) # 50000
Employee.pay_raise_percent = 1.04
print(p1.salary) # 52000
In reality, every access to p1.salary is calling a method that does some math on the real field p1._salary, so any updates to Employee.pay_raise_percent will be seen whenever the salary is requested.
Answered By – Silvio Mayolo
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