On Tue, Oct 10, 2017 at 12:34 PM, Koos Zevenhoven <k7ho...@gmail.com> wrote: > On Tue, Oct 10, 2017 at 3:42 PM, Nick Coghlan <ncogh...@gmail.com> wrote: [..] >> Context managers are merely syntactic sugar for try/finally statements, so >> you can't wave your hands and say a context manager is the only supported >> API: you *have* to break the semantics down and explain what the try/finally >> equivalent looks like. >> >> > > Is this what you're asking? > > assi = cvar.assign(value) > assi.__enter__() > try: > # do stuff involving cvar.value > finally: > assi.__exit__()
But then you *are* allowing users to use "__enter__()" and "__exit__()" directly. Which means that some users *can* experience an unbound growth of context values stack that will make their code run out of memory. This is not similar to appending something to a list -- people are aware that lists can't grow infinitely. But it's not obvious that you can't call "cvar.assign(value).__enter__()" many times. The problem with memory leaks like this is that you can easily write some code and ship it. And only after a while you start experiencing problems in production that are extremely hard to track. Yury _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
