生成器只要在函数体内出现yield关键字，那么再执行函数就不会执行函数代码，会得到一个结果，该结果就是生成器。生成器就是迭代器。def foo(): print('add') yield 1 print('sidhi') yield 2g=foo()next(g)res1=next(g)print(res1)yield的功能：1.yield为我们提供了一种自定义迭代器对象的方法。2.yield与retuen的区别，yield可以返回多次值，所以函数的暂停与继续的转态由yield帮我们保存的。例：range的编写 #range(1,10,2)def bar(x,y,z): while x <= y: yield x x+=zg=bar(1,10,2) print(next(g))案例：编写tail -f error.log |grep 'abc'import time def foo(file): with open(file,'rb') as f: f.seek(0,2) #光标直接到末尾 while Ture: line=f.readline() #.readline()每次只读一行 if line: yield line else: time.sleep(0.03) def grep(line,pater):for i in line: i=i.decode('utf-8') if pater in i: yield ig=grep(foo('error.log'),'abc')for i in g: print(i)yiled表达式形式的用法：def foo(): print('%s is pig' %name) while Ture: bar=yield #bar=yield='1111' print('%s is pig %s' %(name,bar))g=foo('abc')netx(g) #初始化，也可以使用g.send(None)然后g.send(),从代码执行到暂停的位置再将值传给yield ，与next一样。g.send('1111')g.send('2222')面向过程编程: 过程指的是解决问题的步骤，即先设计框架，基于该思路编写程序，是一种机械式方式。优点：复杂问题流程化，进而简单化。缺点：可扩展性差案例：编写grep -rl 'python' /etcimport os def init(funce): def titi(*args,**kawrgs): g=funce(*args,**kawrgs) next(g) return g return titi@init #foo=titidef foo(targrt): while Ture: path_a=yield g=os.wal(path_a) #绝对路径模块 for a,b,c in g: for c1 in c: abc_path=r'%s/%s ' %s(a,c) targrt.send(abc_path)@init def opener(targrt): while Ture: abc_path=yield with open(abc_path,'rb') as f: targrt.send(abc_path,f)@init def cat(targrt): while Ture: abc_path,f=yield for line in f: res=targrt.send((abc_path,line)) if res: break@initdef grep(targrt,pate): pate=pate.encode('utf-8') res=False while Ture: abc_path,line=yield res res=False if pate in line: res=Ture targrt.send(abc_path) @initdef printer(): while Ture: abc_path=yield print('%s' %abc_path)g=foo(opener(cat(grep(printer(),'python'))))g.send(r'/home')