Question

编写一个类，我该如何实现

foo.send（item）？

__iter__允许像生成器一样遍历类，如果我想让它成为协程会怎么样？

Answer 1

def coroutine(func):
    def start(*args,**kwargs):
        cr = func(*args,**kwargs)
        cr.next()
        return cr
    return start

@coroutine
def grep(pattern):
    print "Looking for %s" % pattern
    while True:
        line = (yield)
        if pattern in line:
            print(line)

g = grep("python")
# Notice how you don't need a next() call here
g.send("Yeah, but no, but yeah, but no")
g.send("A series of tubes")
g.send("python generators rock!")
# Looking for python
# python generators rock!

我们可以创建一个包含这样一个协同程序的类，并将对send方法的调用委托给协程：

class Foo(object):
    def __init__(self,pattern):
        self.count=1
        self.pattern=pattern
        self.grep=self._grep()
    @coroutine
    def _grep(self):
        while True:
            line = (yield)
            if self.pattern in line:
                print(self.count, line)
                self.count+=1
    def send(self,arg):
        self.grep.send(arg)

foo = Foo("python")
foo.send("Yeah, but no, but yeah, but no")
foo.send("A series of tubes")
foo.send("python generators rock!")
foo.pattern='spam'
foo.send("Some cheese?")
foo.send("More spam?")

# (1, 'python generators rock!')
# (2, 'More spam?')

请注意foo就像一个协程（只要它有一个send方法），但它是一个类 - 它可以有属性和方法，可以与协程进行交互。

有关更多信息（以及精彩示例），请参阅David Beazley的Curious Course on Coroutines and Concurrency.

python - 支持.send（）为一个类？

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