Summary - Static and class methods

Combine @staticmethod, @classmethod and constants to write a Configuration class.

Summary - Static and class methods

In this group we covered @staticmethod, @classmethod, the factory pattern, class variables and constants. A static method has no self; a class method takes cls.

A factory method returns a new instance; it is named with a from_ prefix. A class variable is shared by all instances. Constants use uppercase. Now we'll combine these into a Bank class.

Exercise Combine the Bank class

Define the Bank class. Add the class variable interest_rate = 0.05 in the body. Add @classmethod and def set_rate(cls, rate):; in the body write cls.interest_rate = rate. Add @staticmethod and def describe():; in the body write return "Bank". Then call Bank.set_rate(0.07) and print(Bank.interest_rate).

Show example solution

# Combine the Bank class
class Bank:
    interest_rate = 0.05
    @classmethod
    def set_rate(cls, rate):
        cls.interest_rate = rate
    @staticmethod
    def describe():
        return "Bank"

Bank.set_rate(0.07)
print(Bank.interest_rate)

Test yourself

What is the first parameter of @classmethod?
- self
- class
- this
- cls
Show answer

cls — The first parameter of @classmethod is cls.
Match the concepts

@staticmethod

Selfless
@classmethod

With cls
from_list

Factory

Complete the class variable

class Bank:
    ____ = 0.05

Show answer

class Bank:
    interest_rate = 0.05

Next lesson: __eq__ and __lt__

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