OOP module

Author: ptyadana

12.Python Object Oriented Programming - JM/01.OOP/class.py

@@ -0,0 +1,47 @@
+# Python Object Oriented Programming by Joe Marini course example
+# Using class-level and static methods
+
+
+class Book:
+    #  Properties defined at the class level are shared by all instances
+    BOOK_TYPES = ("HARDCOVER", "PAPERBACK", "EBOOK")
+
+    #  double-underscore properties are hidden from other classes
+    __booklist = None
+    
+    #  create a class method
+    @classmethod
+    def getbooktypes(cls):
+        return cls.BOOK_TYPES
+
+    #  create a static method
+    @staticmethod
+    def getbooklist():
+        if Book.__booklist == None:
+            Book.__booklist = []
+        return Book.__booklist
+
+    # instance methods receive a specific object instance as an argument
+    # and operate on data specific to that object instance
+    def setTitle(self, newtitle):
+        self.title = newtitle
+
+    def __init__(self, title, booktype):
+        self.title = title
+        if booktype not in self.BOOK_TYPES:
+            raise ValueError(f"{booktype} is not a valid booktype.")
+        else:
+            self.booktype = booktype
+
+#  access the class attribute
+print(Book.getbooktypes())
+
+#  Create some book instances
+b1 = Book("Title 1", "HARDCOVER")
+b2 = Book("Title 2", "PAPERBACK")
+
+#  Use the static method to access a singleton object
+thebooks = Book.getbooklist()
+thebooks.append(b1)
+thebooks.append(b2)
+print(thebooks)

12.Python Object Oriented Programming - JM/01.OOP/class_start.py

@@ -5,21 +5,34 @@
 class Book:
     # the "init" function is called when the instance is
     # created and ready to be initialized
-    def __init__(self, title):
+    def __init__(self, title, author, pages, price):
         self.title = title
-        #  add properties
+        self.author = author
+        self.pages = pages
+        self.price = price
+        self.__secret = "This is secret attribute."
 
     #  create instance methods
+    def getprice(self):
+        if hasattr(self, "_discount"):
+            return self.price - (self.price * self._discount)
+        return self.price
+
+    def setdiscount(self, amount):
+        self._discount = amount
 
 
 #  create some book instances
-b1 = Book("War and Peace")
-b2 = Book("The Catcher in the Rye")
+b1 = Book("War and Peace", "Leo Tolstoy", 1225, 39.95)
+b2 = Book("The Catcher in the Rye", "JD Salinger", 234, 29.99)
 
 #  print the price of book1
-
+print(b1.getprice())
 
 #  try setting the discount
-
+b1.setdiscount(0.20)
+print("after discount : ", b1.getprice())
 
 #  properties with double underscores are hidden by the interpreter
+# print(b1.__secret)
+print(b1._Book__secret)

12.Python Object Oriented Programming - JM/01.OOP/instance.py

@@ -19,9 +19,14 @@ def __init__(self, name):
 n2 = Newspaper("The New York Times")
 
 #  use type() to inspect the object type
-
+print(type(b1))
+print(type(n1))
 
 #  compare two types together
-
+print(type(b1) == type(b2))
+print(type(b2) == type(n2))
 
 #  use isinstance to compare a specific instance to a known type
+print(isinstance(b1, Book))
+print(isinstance(b1, Newspaper))
+print(isinstance(b2, object))