创建型模式：
1、抽象工厂模式
class PetShop:
def __init__(self,animal_factory=None):
self.pet_factory = animal_factory
def show_pet(self):
pet = self.pet_factory.get_pet()
print("This is a lovely",pet)
class Dog:
def speak(self):
return "woof"
def __str__(self):
return "Dog"
class Cat:
def speak(self):
return "meow"
def __str__(self):
return "Cat"
class DogFactory:
def get_pet(self):
return Dog()
class CatFactory:
def get_pet(self):
return Cat()
if __name__ == "__main__":
shop = PetShop()
shop.pet_factory = CatFactory()
shop.show_pet()
2、单例模式
方法一：使用模块，模块是天生的单例模式，把相关的函数和数据定义在一个模块中，导入模块就可以获得一个单例对象了
方法二：使用装饰器
def Singleton(cls):
_instance = {}
def _singleton(*args, **kargs):
if cls not in _instance:
_instance[cls] = cls(*args, **kargs)
return _instance[cls]
return _singleton
@Singleton
class A(object):
a = 1
def __init__(self, x=0):
self.x = x
a1 = A(2)
a2 = A(3)
方法三：基于__new__：
import threading
class Singleton(object):
_instance_lock = threading.Lock()
def __init__(self):
pass
def __new__(cls, *args, **kwargs):
if not hasattr(Singleton, "_instance"):
with Singleton._instance_lock:
if not hasattr(Singleton, "_instance"):
Singleton._instance = object.__new__(cls)
return Singleton._instance
obj1 = Singleton()
obj2 = Singleton()
print(obj1,obj2)
def task(arg):
obj = Singleton()
print(obj)
for i in range(10):
t = threading.Thread(target=task,args=[i,])
t.start()
方法四：基于metaclass
1.类由type创建，创建类时，type的__init__方法自动执行，类() 执行type的 __call__方法(类的__new__方法,类的__init__方法)
2.对象由类创建，创建对象时，类的__init__方法自动执行，对象()执行类的 __call__ 方法
import threading
class SingletonType(type):
_instance_lock = threading.Lock()
def __call__(cls, *args, **kwargs):
if not hasattr(cls, "_instance"):
with SingletonType._instance_lock:
if not hasattr(cls, "_instance"):
cls._instance = super(SingletonType,cls).__call__(*args, **kwargs)
return cls._instance
class Foo(metaclass=SingletonType):
def __init__(self,name):
self.name = name
obj1 = Foo('name')
obj2 = Foo('name')
print(obj1,obj2)
3、原型模式
import copy
class Prototype:
def __init__(self):
self._objects = {}
def register_object(self, name, obj):
"""Register an object"""
self._objects[name] = obj
def unregister_object(self, name):
"""Unregister an object"""
del self._objects[name]
def clone(self, name, **attr):
"""Clone a registered object and update inner attributes dictionary"""
obj = copy.deepcopy(self._objects.get(name))
obj.__dict__.update(attr)
return obj
def main():
class A:
pass
a = A()
prototype = Prototype()
prototype.register_object('a', a)
b = prototype.clone('a', a=1, b=2, c=3)
print(a)
print(b.a, b.b, b.c)
if __name__ == '__main__':
main()
结构型模式：
1、适配器模式
class Dog:
def speak(self):
return "woof"
def __str__(self):
return "Dog"
class Cat:
def speak(self):
return "meow"
def __str__(self):
return "Cat"
class Adaptor:
def __init__(self,obj,adapted_methods):
self.obj= obj
self.__dict__.update(adapted_methods)
def __getattr__(self,attr):
return getattr(self.obj,attr)
if __name__ == "__main__":
objects = []
dog = Dog()
objects.append(Adaptor(dog,dict(make_noise=dog.speak)))
for obj in objects:
print(obj,obj.make_noise())
2、装饰模式
class foo(object):
def f1(self):
print("original f1")
def f2(self):
print("original f2")
class foo_decorator(object):
def __init__(self, decoratee):
self._decoratee = decoratee
def f1(self):
print("decorated f1")
self._decoratee.f1()
def __getattr__(self, name):
return getattr(self._decoratee, name)
u = foo()
v = foo_decorator(u)
v.f1()
v.f2()
3、代理模式
class SalesManager:
def work(self):
print("Sales Manager working...")
def talk(self):
print("Sales Manager ready to talk")
class Proxy:
def __init__(self):
self.busy = 'No'
self.sales = None
def work(self):
print("Proxy checking for Sales Manager availability")
if self.busy == 'No':
self.sales = SalesManager()
time.sleep(2)
self.sales.talk()
else:
time.sleep(2)
print("Sales Manager is busy")
if __name__ == '__main__':
p = Proxy()
p.work()
p.busy = 'Yes'
p.work()
4、外观模式
import time
SLEEP = 0.5
# Complex Parts
class TC1:
def run(self):
print("###### In Test 1 ######")
time.sleep(SLEEP)
print("Setting up")
time.sleep(SLEEP)
print("Running test")
time.sleep(SLEEP)
print("Tearing down")
time.sleep(SLEEP)
print("Test Finished\n")
class TC2:
def run(self):
print("###### In Test 2 ######")
time.sleep(SLEEP)
print("Setting up")
time.sleep(SLEEP)
print("Running test")
time.sleep(SLEEP)
print("Tearing down")
time.sleep(SLEEP)
print("Test Finished\n")
class TC3:
def run(self):
print("###### In Test 3 ######")
time.sleep(SLEEP)
print("Setting up")
time.sleep(SLEEP)
print("Running test")
time.sleep(SLEEP)
print("Tearing down")
time.sleep(SLEEP)
print("Test Finished\n")
# Facade
class TestRunner:
def __init__(self):
self.tc1 = TC1()
self.tc2 = TC2()
self.tc3 = TC3()
self.tests = [i for i in (self.tc1, self.tc2, self.tc3)]
def runAll(self):
[i.run() for i in self.tests]
# Client
if __name__ == '__main__':
testrunner = TestRunner()
testrunner.runAll()
行为型模式：
1、观察者模式
class Subject(object):
def __init__(self):
self._observers = []
def attach(self, observer):
if not observer in self._observers:
self._observers.append(observer)
def detach(self, observer):
try:
self._observers.remove(observer)
except ValueError:
pass
def notify(self, modifier=None):
for observer in self._observers:
if modifier != observer:
observer.update(self)
# Example usage
class Data(Subject):
def __init__(self, name=''):
Subject.__init__(self)
self.name = name
self._data = 0
@property
def data(self):
return self._data
@data.setter
def data(self, value):
self._data = value
self.notify()
class HexViewer:
def update(self, subject):
print('HexViewer: Subject %s has data 0x%x' %
(subject.name, subject.data))
class DecimalViewer:
def update(self, subject):
print('DecimalViewer: Subject %s has data %d' %
(subject.name, subject.data))
# Example usage...
def main():
data1 = Data('Data 1')
data2 = Data('Data 2')
view1 = DecimalViewer()
view2 = HexViewer()
data1.attach(view1)
data1.attach(view2)
data2.attach(view2)
data2.attach(view1)
print("Setting Data 1 = 10")
data1.data = 10
print("Setting Data 2 = 15")
data2.data = 15
print("Setting Data 1 = 3")
data1.data = 3
print("Setting Data 2 = 5")
data2.data = 5
print("Detach HexViewer from data1 and data2.")
data1.detach(view2)
data2.detach(view2)
print("Setting Data 1 = 10")
data1.data = 10
print("Setting Data 2 = 15")
data2.data = 15
if __name__ == '__main__':
main()
2、访问者模式
class Node(object):
pass
class A(Node):
pass
class B(Node):
pass
class C(A, B):
pass
class Visitor(object):
def visit(self, node, *args, **kwargs):
meth = None
for cls in node.__class__.__mro__:
meth_name = 'visit_'+cls.__name__
meth = getattr(self, meth_name, None)
if meth:
break
if not meth:
meth = self.generic_visit
return meth(node, *args, **kwargs)
def generic_visit(self, node, *args, **kwargs):
print('generic_visit '+node.__class__.__name__)
def visit_B(self, node, *args, **kwargs):
print('visit_B '+node.__class__.__name__)
a = A()
b = B()
c = C()
visitor = Visitor()
visitor.visit(a)
visitor.visit(b)
visitor.visit(c)
3、模板模式
ingredients = "spam eggs apple"
line = '-' * 10
# Skeletons
def iter_elements(getter, action):
"""Template skeleton that iterates items"""
for element in getter():
action(element)
print(line)
def rev_elements(getter, action):
"""Template skeleton that iterates items in reverse order"""
for element in getter()[::-1]:
action(element)
print(line)
# Getters
def get_list():
return ingredients.split()
def get_lists():
return [list(x) for x in ingredients.split()]
# Actions
def print_item(item):
print(item)
def reverse_item(item):
print(item[::-1])
# Makes templates
def make_template(skeleton, getter, action):
"""Instantiate a template method with getter and action"""
def template():
skeleton(getter, action)
return template
# Create our template functions
templates = [make_template(s, g, a)
for g in (get_list, get_lists)
for a in (print_item, reverse_item)
for s in (iter_elements, rev_elements)]
# Execute them
for template in templates:
template()
4、迭代器模式
def count_to(count):
"""Counts by word numbers, up to a maximum of five"""
numbers = ["one", "two", "three", "four", "five"]
# enumerate() returns a tuple containing a count (from start which
# defaults to 0) and the values obtained from iterating over sequence
for pos, number in zip(range(count), numbers):
yield number
# Test the generator
count_to_two = lambda: count_to(2)
count_to_five = lambda: count_to(5)
print('Counting to two...')
for number in count_to_two():
print(number, end=' ')
print()
print('Counting to five...')
for number in count_to_five():
print(number, end=' ')
print()
