Python Generator 运行细节验证

class A:
    def __setattr__(self, key, val):
        print(‘set %s to %s‘%(key, val))
        self.__dict__[key] = val

def G():
    e = A()
    i = 0
    while 1:
        e.x = (yield i)
        print(‘    e.x is %s‘%e.x)
        i+=1

def p(s):
    print(‘        out put: %s\n‘% s)
    
g = G()

p(next(g))
p(next(g))
p(g.send(‘x1‘))
p(g.send(‘x2‘))
p(next(g))

>>> 
        out put: 0

set x to None
    e.x is None
        out put: 1

set x to x1
    e.x is x1
        out put: 2

set x to x2
    e.x is x2
        out put: 3

set x to None
    e.x is None
        out put: 4