


Python's combination mode and chain of responsibility mode programming examples
Composite mode
We regard the Composite mode as a complex attribute structure. In fact, there are basically three roles: trunk (define some operations to operate leaves), branches (there are many branches on the trunk) and leaves (think trunk) Objects to be manipulated), the Composite pattern helps us realize: that is, when they act as objects, they are still as easy as other objects, thus providing consistency
python example
class Trunk(object): '''树干''' def __str__(self): pass def subtree(self): pass class Composite(Trunk): def __init__(self, left=None, right=None, length=None): self.left=left self.right=right self.length=length def __str__(self): # 这个结果是在调用subtree()的时候返回 if self.length: return "(" + self.left.__str__() + ", " + self.right.__str__() + ")" + ": " + str(self.length) else: return "(" + self.left.__str__() + ", " + self.right.__str__() + ")" # 这里其实就是一个技巧,通过这个函数返回下一级的对象,也就是它既是对象还可以是对象的容器 def subtree(self): return Composite(self.left, self.right) class Leaf(Trunk): '''叶子类,它没办法继续延伸了''' def __init__(self, name, length=None): self.name = name self.length=length self.left = None self.right = None def __str__(self): return self.name + ": " + str(self.length) def subtree(self): return Leaf(self.name, self.length) if __name__ == "__main__": # 只有叶子那么就直接返回__str__的拼装结果 t1 = Leaf('A', 0.71399) print t1 # 有个2个叶子的组合,返回的是2个叶子的对象的组合 t2 = Composite(Leaf('B', -0.00804), Leaf('C', 0.07470)) print t2 # 这个是嵌套的叶子的组合,树干上面有树枝,树枝上面有叶子 t3 = Composite(Leaf('A', 0.71399), Composite(Leaf('B', -0.00804), Leaf('C', 0.07470), 0.1533), 0.0666) print t3 # 直接通过左右节点找到对应的叶子对象了 t4 = t3.right.right.subtree() print t4 # t3的左树其实就是叶子对象了 t5 = t3.left.subtree() print t5
Chain of Responsibility Model
For example, when we were still studying, the test scores were in several grades, such as 90-100 points, 80-90 points, okay I think Make a feedback that prints your academic performance based on the scores. For example, 90-100 is A+, 80-90 is A, 70-80 is B+... Of course, you can use many methods to achieve it. I will implement a Chain mode here: use A series of classes to respond, but only when it encounters a class suitable for processing it will be processed, similar to the role of case and switch
python example
class BaseHandler: # 它起到了链的作用 def successor(self, successor): self.successor = successor class ScoreHandler1(BaseHandler): def handle(self, request): if request > 90 and request <= 100: return "A+" else: # 否则传给下一个链,下同,但是我是要return回结果的 return self.successor.handle(request) class ScoreHandler2(BaseHandler): def handle(self, request): if request > 80 and request <= 90: return "A" else: return self.successor.handle(request) class ScoreHandler3(BaseHandler): def handle(self, request): if request > 70 and request <= 80: return "B+" else: return "unsatisfactory result" class Client: def __init__(self): h1 = ScoreHandler1() h2 = ScoreHandler2() h3 = ScoreHandler3() # 注意这个顺序,h3包含一个类似于default结果的东西,是要放在最后的,其他的顺序是无所谓的,比如h1和h2 h1.successor(h2) h2.successor(h3) requests = {'zhangsan': 78, 'lisi': 98, 'wangwu': 82, 'zhaoliu': 60} for name, score in requests.iteritems(): print '{} is {}'.format(name, h1.handle(score)) if __name__== "__main__": client = Client()
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