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)