Functional vs Object-Oriented Programming: Python Concepts

Functional vs. Object-Oriented Programming

Object-Oriented Programming (OOP) models problems as objects containing data and methods that perform actions on that data. Functional Programming treats problems as a chain of functions evaluated to produce a result.

Code Output Analysis

• SQUARE [1, 4, 9]: []
• FIB FUNC: 0: 1, 1: 8, 2: 19, 3: 46
• HELLO F: The first prints “Hello world”. The second raises an error because say_hello() is bound to an object but is called without an instance.

Python Methods Explained

A class method takes the class as the first argument. A static method takes no class or instance reference. An instance method takes an instance as an argument.

Intersection of N Lists

To find the intersection of multiple lists, use reduce with set.intersection:

from functools import reduce
in_list = [[1,2,3,4,5], [2,3,4,5,6], [3,4,5,6,7]]
result = reduce(set.intersection, map(set, in_list))
print(result) # Output: {3, 4, 5}

Generator for Merging Sorted Sequences

def merge_sorted_lists(a, b):
    i, j = 0, 0
    while i < len(a) and j < len(b):
        if a[i] < b[j]:
            yield a[i]
            i += 1
        else:
            yield b[j]
            j += 1
    yield from a[i:]
    yield from b[j:]

Refactoring Pi as a Class Method

class Circle:
    pi = 3.14159
    def __init__(self, center, radius):
        self.c = center
        self.radius = radius
    def area(self):
        return self.radius * self.radius * self.pi
    @classmethod
    def constant_pi(cls):
        return cls.pi

Understanding Python Underscores

• _xx: Indicates a non-public member; should not be accessed directly as it is not part of the public API.
• __xx: Used to prevent method overriding by subclasses (name mangling).
• __xx__: Reserved for special Python methods (dunder methods) called internally by the interpreter.

Function Class Point Output

The output for the provided code is: 10 30 10 30