Documenting your new class

Case Study: Building Software in Python

Mark Pedigo, PhD

Principal Data Scientist

Roadmap

Roadmap showcasing what parts of the project we've finished and which we'll be starting.

Your Class Hierarchy

BasicCalculator
- Performs basic arithmetic
FinancialCalculator
- Child of BasicCalculator
- Adds financial features, such as interest rate
MortgageCalculator
- Inherits from FinancialCalculator
- Combines functionality of both classes

Docstrings

Benefits of docstrings
- Provides clear, concise explanations of code
How to create a docstring
- Add a string literal as the first statement
- Write an explanation of purpose and functionality

def MortgageClass(FinancialCalculator):
    """
    MortgageClass extends the FinancialCalculator to mortgage specific calculations.
    """
    ...

Add attributes to the Mortgage Calculator class

    class MortgageCalculator(FinancialCalculator):
    def __init__(self, loan_amount, annual_interest_rate, years):
        super().__init__()
        self.loan_amount = loan_amount
        self.monthly_interest_rate = self.monthly_interest(annual_interest_rate)

    self.months = years * 12

    # Create an attribute to hold the monthly payment amount.
    self.monthly_payment = self.calculate_monthly_payment()

Keep Track of Functionality of Classes

Use dir(ClassName) to get a list of the functions of a class

dir(MortgageCalculator)

['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', 
'__format__', '__ge__', '__getattribute__', '__getstate__', '__gt__', 
'__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', 
'__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__',
'__sizeof__', '__str__', '__subclasshook__', '__weakref__', 
'difference', 'monthly_interest', 'months_from_years',
'power', 'product', 'quotient', 'sum']

Let's practice!

Case Study: Building Software in Python