python3 和 python2 系列的用法

'''python3 下面这样写没有问题'''

db = momoko.Pool(dsn='dbname=%s user=%s' % (config.db.database, config.db.user), size=2)

@tornado.gen.coroutine
def execute(self, query, *args):
result = yield momoko.Op(self.db.execute, query, args, cursor_factory=psycopg2.extras.DictCursor)
return result

python2 下面会提示 python version < 3.3 do not allow 'return' .....

所以我把

@tornado.gen.coroutine
def execute(self, query, *args):
result = yield momoko.Op(self.db.execute, query, args, cursor_factory=psycopg2.extras.DictCursor)
return result

return result 直接去掉，写了一个 self.finish()

然后另外一个地方直接这样调用

@gen.coroutine
def get(self):
query = 'INSERT INTO public.user (name, password) VALUES (%s, %s);'
try:
yield self.execute(query,'sss','333')
except (psycopg2.Warning, psycopg2.Error) as error:
self.write(str(error))
self.finish()

这样会有问题么？？

query

args

result

7 条回复 • 2014-11-23 19:00:10 +08:00

ryd994

2014-11-23 14:20:39 +08:00 via Android

return()吧

ryd994

2014-11-23 14:22:13 +08:00 via Android

我错了，没事了

p8p8

2014-11-23 14:22:39 +08:00

@ryd994 return()吧 ??

result = yield momoko.Op(self.db.execute, query, args, cursor_factory=psycopg2.extras.DictCursor)
return result

这里改成

result = yield momoko.Op(self.db.execute, query, args, cursor_factory=psycopg2.extras.DictCursor)
return()

这样吗？

我怎么感觉你的回答好虚啊。。。不过还是谢谢你。

p8p8

2014-11-23 14:23:06 +08:00

@ryd994 哈哈哈，没事，大家一起学习进步！

iceout

2014-11-23 14:28:27 +08:00

http://tornado.readthedocs.org/en/branch3.2/gen.html#decorators
文档中写了。。。

Coroutines may “return” by raising the special exception Return(value).In Python 3.3+, it is also possible for the function to simply use the return value statement (prior to Python 3.3 generators were not allowed to also return values).

p8p8

2014-11-23 14:52:17 +08:00

@iceout 嗯，然后呢？2系列中应该怎么用呢？

iceout

2014-11-23 19:00:10 +08:00

@p8p8 第一句。。raise exception

文档中的例子：

@gen.coroutine
def fetch_json(url):
response = yield AsyncHTTPClient().fetch(url)
raise gen.Return(json_decode(response.body))