update WhenObjectsAreAlike

Author: rambasnet

notebooks/00-TableOfContents.ipynb

@@ -71,7 +71,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.10.8"
+   "version": "3.9.13"
   }
  },
  "nbformat": 4,

notebooks/ObjectOrientedDesign.ipynb

@@ -223,7 +223,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.10.8"
+   "version": "3.9.13"
   }
  },
  "nbformat": 4,

notebooks/WhenObjectsAreAlike.ipynb

@@ -10,8 +10,8 @@
     "- in programming, duplicate code is considered evil\n",
     "    - difficult to debug and maintain code\n",
     "- there are many ways to merge pieces of code or objects that have similar functions\n",
-    "- the concept of inheritance introduced earlier is an important one that allows us to create **is-a** relationship between two or more classes\n",
-    "    - inherit common code from base/superclass and extend it with specific details in each subclass"
+    "- the concept of inheritance allows us to create **is-a** relationship between two or more classes\n",
+    "    - inherit common code from base/superclass and extend/override it with specific details in each subclass (aka Polymorphism)"
    ]
   },
   {
@@ -23,7 +23,9 @@
     "\n",
     "- technically every class inherits from the built-in *object* class\n",
     "- generally, we extend the base/parent/super class and customize/add more functionalities to the derived/child class\n",
-    "- child class inherits methods and attributes defined in parent classes"
+    "- child class inherits methods and attributes defined in parent classes\n",
+    "\n",
+    "![](resources/UML-inheritance.png)"
    ]
   },
   {
@@ -160,8 +162,8 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "# each object all has access to class variable\n",
-    "# not common notation\n",
+    "# each object has access to class variable\n",
+    "# not common notation; confusing as if all_contacts is an instance variable\n",
     "pprint(c.all_contacts)"
    ]
   },
@@ -172,6 +174,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
+    "# better notation\n",
     "pprint(Contact.all_contacts)"
    ]
   },
@@ -1047,7 +1050,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 161,
+   "execution_count": 6,
    "id": "cb72de1f",
    "metadata": {},
    "outputs": [],
@@ -1083,7 +1086,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 162,
+   "execution_count": 7,
    "id": "652387cb",
    "metadata": {},
    "outputs": [
@@ -1107,7 +1110,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 163,
+   "execution_count": 8,
    "id": "86ef7003",
    "metadata": {},
    "outputs": [
@@ -1138,7 +1141,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 164,
+   "execution_count": 9,
    "id": "8be64c14",
    "metadata": {},
    "outputs": [],
@@ -1173,7 +1176,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 165,
+   "execution_count": 10,
    "id": "ee517faa",
    "metadata": {},
    "outputs": [
@@ -1195,7 +1198,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 166,
+   "execution_count": 11,
    "id": "74dce83f",
    "metadata": {},
    "outputs": [
@@ -1226,7 +1229,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 167,
+   "execution_count": 12,
    "id": "a7271b87",
    "metadata": {},
    "outputs": [],
@@ -1236,7 +1239,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 168,
+   "execution_count": 13,
    "id": "d1381eba",
    "metadata": {},
    "outputs": [
@@ -1258,10 +1261,22 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 14,
    "id": "98b3a4c6",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "(<class '__main__.Subclass_S'>,\n",
+      " <class '__main__.RightSubclass_S'>,\n",
+      " <class '__main__.LeftSubclass_S'>,\n",
+      " <class '__main__.BaseClass_S'>,\n",
+      " <class 'object'>)\n"
+     ]
+    }
+   ],
    "source": [
     "pprint(Subclass_S.__mro__)"
    ]
@@ -1457,7 +1472,7 @@
     "- duck-test: \"If it walks like a duck and it quacks like a duck, then it must be a duck\"\n",
     "- to determine whether a function can be applied to a new type, we apply Python's fundamental rule of polymorphism, called duck typing rule: if all of the operations inside the function can be applied to the type, the function can be applied to the type\n",
     "- it allows us to use *any* object that provides the required behavior without forcing it to be a subclass\n",
-    "- `FlacFile` doesn't inherit from AudioFile but it can be interacted with within Python using the exact same interface!"
+    "- `FlacFile` doesn't inherit from AudioFile but it can be interacted with using the exact same interface!"
    ]
   },
   {
@@ -1506,7 +1521,8 @@
     "## Mixin Design Pattern\n",
     "\n",
     "- **Mixin** is the simplest and most useful form of multiple inheritance\n",
-    "- a mixin class definition is not intended to exist on its own but is meant to be inherited by some other class\n",
+    "- a mixin class is not meant to be instantiated, but is meant to be inherited by some other class\n",
+    "    - it is mixed in with other classes to extend their behavior\n",
     "- the goal is to extend and provide extra functionality without worrying about the correctness of \"is-a\" relationship\n",
     "- mixins are sometimes described as being \"including\" or \"using\" rather than \"inheriting\"\n",
     "- mixins encourage code reuse and can be used to avoid the inheritance ambiguity that multiple inheritance can cause (**diamond problem**)\n",
@@ -1516,6 +1532,43 @@
     "- Employee and Address are NOT AsDictionaryMixin, but both of them \"use\" AsDictionaryMixin mixin"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "id": "e8107f89",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "[LOG]: Dog is barking\n",
+      "Woof!\n"
+     ]
+    }
+   ],
+   "source": [
+    "# Define a Mixin\n",
+    "class LoggingMixin:\n",
+    "    def log(self, message):\n",
+    "        print(f\"[LOG]: {message}\")\n",
+    "\n",
+    "# Define a Base Class\n",
+    "class Animal:\n",
+    "    def speak(self):\n",
+    "        pass\n",
+    "\n",
+    "# Use the Mixin\n",
+    "class Dog(Animal, LoggingMixin):\n",
+    "    def speak(self):\n",
+    "        self.log(\"Dog is barking\")\n",
+    "        return \"Woof!\"\n",
+    "\n",
+    "# Usage\n",
+    "dog = Dog()\n",
+    "print(dog.speak())  # Output: [LOG]: Dog is barking \\n Woof!"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 180,
@@ -1775,6 +1828,8 @@
     "### L: Liskov Substitution\n",
     "- named after Barbara Liskov creator of CLU programming language\n",
     "- any subclass can be substituted for its superclass\n",
+    "    - any code that uses superclass can be replaced with it's subclass without breaking any code!\n",
+    "    - the inverse is not true!\n",
     "- the essence of polymorphism\n",
     "\n",
     "### I: Interface Segregation\n",
@@ -1796,10 +1851,10 @@
     "- \"You wanted a banana but what you got was a gorilla holding the banana and the entire jungle\" - Joe Armstrong\n",
     "- inheritance is a powerful tool but it can be misused\n",
     "- alternatives may be better to avoid the inheritance tax:\n",
-    "    - interfaes and protocols\n",
+    "    - interfaces and protocols\n",
     "    - delegation\n",
-    "    - mixins and traits\n",
-    "- interfaces and protocols give us prolymorphism without inheritance\n",
+    "    - mixins\n",
+    "- interfaces and protocols give us polymorphism without inheritance\n",
     "- delegation is a way to use composition instead of inheritance\n",
     "- delegate to services - Has-A relationship Trumps Is-A relationship\n",
     "- use mixins to share code and functionality\n"
@@ -1846,7 +1901,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.10.8"
+   "version": "3.9.13"
   },
   "vscode": {
    "interpreter": {