[Python-Dev] PEP 492 and types.coroutine (original) (raw)
Ethan Furman ethan at stoneleaf.us
Sat May 2 19:04:16 CEST 2015
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According to https://www.python.org/dev/peps/pep-0492/#id31:
The [types.coroutine] function applies CO_COROUTINE flag to generator-function's code object, making it return a coroutine object.
Further down in https://www.python.org/dev/peps/pep-0492/#id32:
[await] uses the yield from implementation with an extra step of validating its argument. await only accepts an awaitable, which can be one of:
...
- A generator-based coroutine object returned from a generator
decorated with types.coroutine().If I'm understanding this correctly, type.coroutine's only purpose is to add a flag to a generator object so that await will accept it.
This raises the question of why can't await simply accept a generator object? There is no code change to the gen obj itself, there is no behavior change in the gen obj, it's the exact same byte code, only a flag is different.
types.coroutine feels a lot like unnecessary boiler-plate.
--
Ethan
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