回调函数是实现异步操作的常用手法
1、callback版本的示例，其中framework调用logic，在完成某些操作或者接收到信号后，用callback返回异步结果
#!/usr/bin/env python2.7 def framework(logic,callback):
s=logic()
print "[FX] logic:",s
print "[FX] do something..." for i in xrange(1000000):
a=i+1
callback("async:"+s) def logic():
s="mylogic"
return s def callback(s):
print s framework(logic,callback)
2、使用yield改进的blocking style版本：
#!/usr/bin/env python2.7
#-*- coding:utf8 -*- def framework(logic):
try:
it = logic()
s = next(it) print "[FX] logic:",s
print "[FX] do something" f=open("test.txt",'w')
for i in xrange(1000000000):
f.write(str(i)+'\n')
f.close() it.send("async:" + s)
except StopIteration:
pass def logic():
s = "mylogic"
r = yield s print r framework(logic)