Python Programming

You have seen the special constructor method __init__() earlier.

Python offers more magic or dunder methods that can be used to make your classes act like Python built-in types (dunder == double underscores).

Let’s look at a few example magic methods and how they can be useful.

A more readable str representation of an object.

We can use str() in Python to return a string representation of any objects. By default, str(your_instance) will return something like '<__main__.Person object at 0x7fa89a45a1f0>'. The print() function will also internally convert an object into a string before printing them out.

If you would like something more readable and informative, say "A Person named Josiah aged 20", you can override the default behaviour with a magic __str__() method.

Below is an example. Run the code with and without the __str__(self) method, and check the output to compare the difference!

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class Vector: 
    def __init__(self, x, y): 
        self.x = x 
        self.y = y

    def __str__(self): 
        return f"Vector ({self.x}, {self.y})"

v = Vector(1, 2) 
print(v)

Try it yourself!

Now try making the Person class return a more readable and informative string representation of the object. For example, you could return something like "A Person named Josiah aged 20 from malaysia".

class Person:
    def __init__(self, name, age, nationality="uk"):
        self.name = name
        self.age = age
        self.nationality = nationality

    def __str__(self):
        # TODO: Complete this!
        pass


lecturer = Person("Josiah", 20, "malaysia")
print(lecturer)

You can check your implementation against mine on the next page.