add mro

Author: rubada

03.OOP_Pillars/01.oop_pillar_scripts/01d.MRO.py

@@ -0,0 +1,42 @@
+# What is a Method Resolution Order (MRO)?
+# MRO is the classes (Superclasses, subclasses) order that Python searches for
+# attributes or methods.
+# First Python searches for the methods or attributes in the class itself, then
+# it follows the order of inheritance.
+# Let's take an example:
+class Parent:
+
+    def who_I_am(self):
+        return "I am the Parent"
+
+
+class Child1(Parent):
+
+    def who_I_am(self):
+        return "I am Child1"
+
+
+class Child2(Parent):
+
+    def who_I_am(self):
+        return "I am Child2"
+
+
+class GrandChild(Child1, Child2):
+
+    def who_I_am(self):
+        return "I am the GrandChild"
+
+
+# To get the MRO we use the mro() method:
+# print(GrandChild.mro())
+
+# That means if I want to execute the who_I_am(), if the object is created
+# from the GrandChild class, then Python will search the Grandchild class
+# first.
+
+grand_child = GrandChild()
+# print(grand_child.who_I_am())
+
+# That's why we should be extra careful when using multi-level inheritance,
+# because it may lead to undesirable results.