[Python-Dev] Rewrite @contextlib.contextmanager in C (original) (raw)

Serhiy Storchaka storchaka at gmail.com
Tue Aug 9 15:58:14 EDT 2016

On 09.08.16 00:59, Chris Angelico wrote:

class TooSimpleContextManager: """Now this time you've gone too far.""" def init(self, func): self.func = func def call(self): self.gen = self.func() return self def enter(self): next(self.gen) def exit(self, type, value, traceback): try: next(self.gen) except StopIteration: pass [...] My numbers are:

0.320 secs 1.354 secs slowdown: -4.23x 0.899 secs slowdown: -2.81x 0.831 secs slowdown: -2.60x 0.868 secs slowdown: -2.71x

I have got a slowdown 1.74x with TooSimpleContextManager with following implementation of enter and exit:

 def __enter__(self):
     for res in self.gen:
         return res
     raise RuntimeError("generator didn't yield")
 def __exit__(self, type, value, traceback):
     for _ in self.gen:
         raise RuntimeError("generator didn't stop")

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