PythonS12-day4学习笔记

# 迭代器、装饰器、生成器
# 迭代器
li = [1, 3, 'he', '&']
n = iter(li)
print(n.__next__())
import os, sys

# 生成器
def func():
    for i in xrange(10):
        yield (i)
        print(i)

 # 装饰器
 #使用装饰函数在函数执行前和执行后分别附加额外功能
 '''示例2: 替换函数(装饰)
 装饰函数的参数是被装饰的函数对象，返回原函数对象
 装饰的实质语句: myfunc = deco(myfunc)'''
 def deco(func):
     print("before myfunc() called.")
     func()
     print("  after myfunc() called.")
     return func
 def myfunc():
     print(" myfunc() called.")
 myfunc = deco(myfunc)
 myfunc()
 myfunc()
 #使用语法糖@来装饰函数
 '''示例3: 使用语法糖@来装饰函数，相当于“myfunc = deco(myfunc)”
 但发现新函数只在第一次被调用，且原函数多调用了一次'''
 def deco(func):
     print("before myfunc() called.")
     func()
     print("  after myfunc() called.")
     return func
 @deco
 def myfunc():
     print(" myfunc() called.")
 myfunc()
 myfunc()

 #用内嵌包装函数来确保每次新函数都被调用
 def deco(func):
     def _deco():
         print("before myfunc() called.")
         func()
         print("  after myfunc() called.")
         # 不需要返回func，实际上应返回原函数的返回值
     return _deco
 @deco
 def myfunc():
     print(" myfunc() called.")
     return 'ok'
 myfunc()
 myfunc()
 #对带参数的函数进行装饰
 def deco(func):
     def _deco(a, b):
         print("before myfunc() called.")
         ret = func(a, b)
         print("  after myfunc() called. result: %s" % ret)
         return ret
     return _deco
 @deco
 def myfunc(a, b):
     print(" myfunc(%s,%s) called." % (a, b))
     return a + b
 myfunc(1, 2)
 myfunc(3, 4)
 #对参数数量不确定的函数进行装饰
 '''示例6: 对参数数量不确定的函数进行装饰，
 参数用(*args, **kwargs)，自动适应变参和命名参数'''
 def deco(func):
     def _deco(*args, **kwargs):
         print("before %s called." % func.__name__)
         ret = func(*args, **kwargs)
         print("  after %s called. result: %s" % (func.__name__, ret))
         return ret
     return _deco
 @deco
 def myfunc(a, b):
     print(" myfunc(%s,%s) called." % (a, b))
     return a+b
 @deco
 def myfunc2(a, b, c):
     print(" myfunc2(%s,%s,%s) called." % (a, b, c))
     return a+b+c
 myfunc(1, 2)
 myfunc(3, 4)
 myfunc2(1, 2, 3)
 myfunc2(3, 4, 5)

 #让装饰器带参数
 def deco(arg):
     def _deco(func):
         def __deco():
             print("before %s called [%s]." % (func.__name__, arg))
             func()
             print("  after %s called [%s]." % (func.__name__, arg))
         return __deco
     return _deco

 @deco("mymodule")
 def myfunc():
     print(" myfunc() called.")

 @deco("module2")

 def myfunc2():
     print(" myfunc2() called.")
 myfunc()
 myfunc2()
 #让装饰器带 类 参数
 '''示例8: 装饰器带类参数'''
 class locker:
     def __init__(self):
         print("locker.__init__() should be not called.")
     @staticmethod
     def acquire():
         print("locker.acquire() called.（这是静态方法）")
     @staticmethod
     def release():
         print("  locker.release() called.（不需要对象实例）")
 def deco(cls):
     '''cls 必须实现acquire和release静态方法'''
     def _deco(func):
         def __deco():
             print("before %s called [%s]." % (func.__name__, cls))
             cls.acquire()
             try:
                 return func()
             finally:
                 cls.release()
         return __deco
     return _deco
 @deco(locker)
 def myfunc():
     print(" myfunc() called.")
 myfunc()
 myfunc()
 #装饰器带类参数，并分拆公共类到其他py文件中，同时演示了对一个函数应用多个装饰器
 '''mylocker.py: 公共类 for 示例9.py'''
 class mylocker:
     def __init__(self):
         print("mylocker.__init__() called.")
     @staticmethod
     def acquire():
         print("mylocker.acquire() called.")
     @staticmethod
     def unlock():
         print("  mylocker.unlock() called.")
 class lockerex(mylocker):
     @staticmethod
     def acquire():
         print("lockerex.acquire() called.")
     @staticmethod
     def unlock():
         print("  lockerex.unlock() called.")
 def lockhelper(cls):
     '''cls 必须实现acquire和release静态方法'''
     def _deco(func):
         def __deco(*args, **kwargs):
             print("before %s called." % func.__name__)
             cls.acquire()
             try:
                 return func(*args, **kwargs)
             finally:
                 cls.unlock()
         return __deco
     return _deco
 '''示例9: 装饰器带类参数，并分拆公共类到其他py文件中
 同时演示了对一个函数应用多个装饰器'''
 from mylocker import *
 class example:
     @lockhelper(mylocker)
     def myfunc(self):
         print(" myfunc() called.")
     @lockhelper(mylocker)
     @lockhelper(lockerex)
     def myfunc2(self, a, b):
         print(" myfunc2() called.")
         return a + b
 if __name__=="__main__":
     a = example()
     a.myfunc()
     print(a.myfunc())
     print(a.myfunc2(1, 2))
     print(a.myfunc2(3, 4))

 # 递归
 #斐波那契数列
 def func(arg1, arg2, stop):
     if arg1 == 0:
         print(arg1, arg2)
     arg3 = arg1 + arg2
     print(arg3)
     if arg3 < stop:
         func(arg2, arg3, stop)

 func(0, 1, 60)

 #算法基础之二分查找
 def data_search(data,find_d):
     mid=int(len(data)/2)
     if len(data)>=1:
         if data[mid]>find_d:
             print("data in thie left of [%s]"%data[mid])
             data_search(data[:mid],find_d)
         elif data[mid]<find_d:
             print("data in right of [%s]"%data[mid])
             data_search(data[mid:],find_d)
         else:
             print("found find_d",data[mid])
     else:
         print("cannot find`````")
 if __name__=="__main__":
     data=list(range(1,60000000))
     data_search(data,99)

 #二维数组旋转
 data=[[col for col in range(4)]for row in range(4)]
 print(data)
 for rindex,row in enumerate(data):
     print(rindex,row)
     for cindex in range(rindex,len(row)):
         tmp=data[cindex][rindex]
         data[cindex][rindex]=row[cindex]
         data[rindex][cindex]=tmp
     print('-------------------------')
     for r in data:print(r)