设计模式之责任链模式

设计模式之责任链模式

 例一：

from abc import ABCMeta,abstractmethod

class BaseHandler(metaclass=ABCMeta):
    @abstractmethod
    def handle_leave(self,days):
        pass

class GeneralManagerHandler(BaseHandler):
    def handle_leave(self,days):
        if days < 10:
            print('总经理批准%s天假期'%days)
        else:
            print('你想多了吧......')

class DepartmentManagerHandler(BaseHandler):
    def __init__(self):
        self.leader = GeneralManagerHandler()
    def handle_leave(self,days):
        if days < 5:
            print('部门经理批准%s天假期'%days)
        else:
            print('部门经理无权配准%s天假,需要向总经理申请'%days)
            self.leader.handle_leave(days)

class ProjectDirectorHandler(BaseHandler):
    def __init__(self):
        self.leader = DepartmentManagerHandler()
    def handle_leave(self,days):
        if days < 3:
            print('项目主管批准%s天假期'%days)
        else:
            print('项目主管无权配准%s天假,需要向部门经理经理申请' % days)
            self.leader.handle_leave(days)

employee = ProjectDirectorHandler()
employee.handle_leave(15)

 例二：

from abc import ABCMeta,abstractmethod
class BaseHandler(metaclass=ABCMeta):
    @abstractmethod
    def add_event(self,func):
        pass
    @abstractmethod
    def handle(self):
        pass

class BodyHandler(BaseHandler):
    def __init__(self):
        self.func = None
    def add_event(self,func):
        self.func = func
    def handle(self):
        if self.func:
           return self.func()
        else:
            print('ending......')

class ElementHandler(BaseHandler):
    def __init__(self,leader):
        self.func = None
        self.leader = leader
    def add_event(self,func):
        self.func = func
    def handle(self):
        if self.func:
            return self.func()
        else:
            return self.leader.handle()

body = {'type':'body','name':'body','children':[],'father':None,'event_handler':None}
div = {'type':'div','name':'div','children':[],'father':body,'event_handler':None}
span = {'type':'span','name':'span','children':[],'father':div,'event_handler':None}

body['children'].append(div)
div['children'].append(span)

body['event_handler'] = BodyHandler()
div['event_handler'] = ElementHandler(div['father']['event_handler'])
span['event_handler'] = ElementHandler(span['father']['event_handler'])

def bind_event(element,func):
    element['event_handler'].add_event(func)

def func_body():
    print('这是给body的函数')

def func_div():
    print('这是给div的函数')

def func_span():
    print('这是给span的函数')

bind_event(body,func_body)
# bind_event(div,func_div)
# bind_event(span,func_span)

span['event_handler'].handle()
div['event_handler'].handle()
body['event_handler'].handle()