[Python-Dev] PEP 492 vs. PEP 3152, new round (original) (raw)

Ethan Furman ethan at stoneleaf.us
Thu Apr 30 18:15:41 CEST 2015

On 04/29, Yury Selivanov wrote:

Because you want operators to be resolved in the order you see them, generally.

You want '(await -fut)' to: 1. Suspend on fut; 2. Get the result; 3. Negate it. This is a non-obvious thing. I would myself interpret it as: 1. Get fut.neg(); 2. await on it.

Both you and Paul are correct on this, thank you. The proper resolution of

await -coro()

is indeed to get the result of coro(), call it's neg method, and then await on that.

And that is perfectly reasonable, and should not be a SyntaxError; what it might be is an AttributeError (no neg method) or an AsyncError (neg returned non-awaitable object), or might even just work [1]... but it definitely should /not/ be a SyntaxError.

-- Ethan

[1] http://stackoverflow.com/q/7719018/208880

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