black formatting, readme

Author: dancergraham

chapter04_factory/pizza_abstract_factory.py

@@ -213,15 +213,15 @@ def __str__(self):
             result.append(self.cheese)
 
         if self.veggies:
-            result.append(", ".join(map(str,self.veggies)))
+            result.append(", ".join(map(str, self.veggies)))
 
         if self.clam:
             result.append(self.clam)
 
         if self.pepperoni:
             result.append(self.pepperoni)
-        
-        return "\n".join(map(str, result))+"\n"
+
+        return "\n".join(map(str, result)) + "\n"
 
 
 class CheesePizza(Pizza):
@@ -338,4 +338,4 @@ def pizza_test_drive():
 
 
 if __name__ == "__main__":
-    pizza_test_drive()
+    pizza_test_drive()

chapter04_factory/readme.md

@@ -2,6 +2,10 @@
 
 **Simple Factory**: A class which chooses which product class to instantiate and return, based upon method parameters.
 
-**Factory Method**: Define an interface for creating an object, but let subclasses decide which class to instantiate. The Factory method lets a class defer instantiation it uses to subclasses.
+**Factory Method**: Defines an interface for creating an object, but lets subclasses decide which class to instantiate. The Factory method lets a class defer instantiation to subclasses.
 
-**Abstract Factory**: Provide an interface for creating families of related or dependent objects without specifying their concrete classes.
+For instance the `PizzaStore` abstract class in this repo provides an abstract `create_pizza` interface for creating one product.  
+
+**Abstract Factory**: Provides an interface for creating families of related or dependent objects without specifying their concrete classes.
+
+For instance the `PizzaIngredientFactory` abstract class defines an interface for a family of products.