Added prototype pattern example

Author: avidLearnerInProgress

pydesignpatterns/creational/prototype_shape.py

@@ -0,0 +1,146 @@
+"""
+Author: CHIRAG SHAH
+Created On: 26th July 2018
+"""
+
+import inspect, sys, copy
+import matplotlib.pyplot as plt
+from pathlib import Path, PureWindowsPath
+from abc import ABCMeta, abstractmethod
+
+sys.path.append(str(Path(__file__).resolve().parent.parent))
+from utility import class_diagram, output_image
+
+class Shape(metaclass = ABCMeta):
+"""
+Abstract class
+"""
+def __init__(self):
+self.id = None
+self.type = None
+
+@abstractmethod
+def draw(self):
+pass
+
+def get_type(self):
+return self.type
+
+def get_id(self):
+return self.id
+
+def set_id(self, id):
+self.id = id
+
+def clone(self):
+return copy.copy(self)
+
+class Rectangle(Shape):
+"""
+Concrete class extending base class
+"""
+
+def __init__(self):
+super().__init__()
+self.type = "Rectangle"
+
+def draw(self):
+print("Drawing Rectangle with draw()..")
+
+class Circle(Shape):
+"""
+Concrete class extending base class
+"""
+
+def __init__(self):
+super().__init__()
+self.type = "Circle"
+
+def draw(self):
+print("Drawing Circle with draw()..")
+
+class Square(Shape):
+"""
+Concrete class extending base class
+"""
+
+def __init__(self):
+super().__init__()
+self.type = "Square"
+
+def draw(self):
+print("Drawing Square with draw()..")
+
+class ShapeCacheAddr:
+"""
+Maps classes with their id's in dict.
+Returns object clones when needed
+"""
+cache = {}
+
+@staticmethod
+def get_shape(shape_id):
+shape = ShapeCacheAddr.cache.get(shape_id, None)
+return shape.clone()
+
+@staticmethod
+def load():
+circle = Circle()
+circle.set_id("1")
+ShapeCacheAddr.cache[circle.get_id()] = circle
+
+square = Square()
+square.set_id("2")
+ShapeCacheAddr.cache[square.get_id()] = square
+
+rectangle = Rectangle()
+rectangle.set_id("3")
+ShapeCacheAddr.cache[rectangle.get_id()] = rectangle
+
+def test_prototype():
+"""
+Demonstration of prototype pattern
+"""
+
+ShapeCacheAddr.load()
+circle = ShapeCacheAddr.get_shape("1")
+print(circle.get_type())
+
+square = ShapeCacheAddr.get_shape("2")
+print(square.get_type())
+
+rectangle = ShapeCacheAddr.get_shape("3")
+print(rectangle.get_type())
+
+def get_code():
+"""
+@return-values: source code
+"""
+a = inspect.getsource(Shape)
+b = inspect.getsource(Circle)
+c = inspect.getsource(Square)
+d = inspect.getsource(Rectangle)
+e = inspect.getsource(ShapeCacheAddr)
+f = inspect.getsource(test_prototype)
+
+return a + '\n' + b + '\n' + c + '\n' + d + '\n' + e + '\n' + f
+
+def get_classdiagram():
+"""
+@return-values: matplotlib object with class diagram
+"""
+
+diagram = class_diagram("prototype.png")
+plt.show()
+return diagram
+
+def get_outputimage():
+"""
+@return-values: matplotlib object with code output
+"""
+
+output = output_image("prototype_shape.png")
+plt.show()
+return output
+
+test_prototype()