mro_attribute_demo

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Filename: mro_attribute_demo.py
# Version: 1.0.0
# Author: Jeoi Reqi

"""
This script demonstrates the usage of the __mro__ attribute in Python, which stands for Method Resolution Order.
It defines three classes: A, B, and C. Class C inherits from both classes A and B, showcasing multiple inheritance.

Requirements:
- Python 3.x

Functions:
- line(): A utility function to print divider lines for better readability.

Usage:
1. Run the script using Python 3.x interpreter.
2. The script will print the method resolution order (__mro__) for classes A, B, and C.
3. It will also perform hasattr checks to verify if instances of classes A, B, and C have the __mro__ attribute.

Additional Notes:
- The __mro__ attribute provides insight into the sequence of classes that Python will search to resolve method calls in a class hierarchy.
- Instances of classes do not inherit from 'type', hence they do not have the __mro__ attribute.
- This script serves as a basic example to understand the method resolution order and multiple inheritance in Python.
- It's recommended to run the script in an environment with Python 3.x installed to ensure compatibility.
"""

class A: pass
class B: pass

class C(A, B): pass

# Function to print divider lines
def line():
    print("-" * 94)

line()
print("\n\t\t\t:: Explanation for A.__mro__ ::\n")
line()
print("A.__mro__ represents the method resolution order for class A.\n")
print("- It shows the sequence of classes that Python will search to resolve method calls for class A.")
print("- In this case, A.__mro__ is:\n\n\t", A.__mro__)
print()

line()
print("\n\t\t\t:: Explanation for B.__mro__ ::\n")
line()
print("B.__mro__ represents the method resolution order for class B.\n")
print("- It shows the sequence of classes that Python will search to resolve method calls for class B.")
print("- In this case, B.__mro__ is:\n\n\t", B.__mro__)
print()

line()
print("\n\t\t\t:: Explanation for C.__mro__ ::\n")
line()
print("C.__mro__ represents the method resolution order for class C.\n")
print("- It shows the sequence of classes that Python will search to resolve method calls for class C.")
print("- In this case, C.__mro__ is:\n\n\t", C.__mro__)
print()

a = A()
b = B()
c = C()

line()
print("\n\t\t\t:: Explanation for hasattr checks ::\n")
line()
print("The following assertions check if the objects have the __mro__ attribute.\n")
print("\t\t\tFor instance a:", hasattr(a, '__mro__'))
print("\t\t\tFor instance b:", hasattr(b, '__mro__'))
print("\t\t\tFor instance c:", hasattr(c, '__mro__'))
print("\nSince instances do not inherit from 'type', they do not have this attribute.\n")
line()