coburnw

# https://stackoverflow.com/a/5961102
# Note python3 has a different declaration than the so post

class ShapeFactory(type):
    """Shape Factory"""

    def __call__(cls, selector, *args):
        if cls is Shape:
            # select a new object
            print('factory build:', selector)

coburnw

# https://stackoverflow.com/a/5961102

class Shape(object):
    def __new__(cls, *args):
        selector = args[0]
        print('factory build:', selector)
        if cls is Shape:
            # Create a subclassed shape from a name
            if selector == 'rectangle': return super(Shape, cls).__new__(Rectangle)
            if selector == 'triangle': return super(Shape, cls).__new__(Triangle)