PythonExtra/tests/basics/generator_pend_throw.py.exp

0
1
raised ValueError()
ret was: None
raised OSError()
raised ValueError('generator already executing',)
raised ValueError('generator already executing',)
0
ignore CancelledError
1
raised CancelledError()
None
CancelledError()
CancelledError()
1
py/objgenerator: Allow to pend an exception for next execution. This implements .pend_throw(exc) method, which sets up an exception to be triggered on the next call to generator's .__next__() or .send() method. This is unlike .throw(), which immediately starts to execute the generator to process the exception. This effectively adds Future-like capabilities to generator protocol (exception will be raised in the future). The need for such a method arised to implement uasyncio wait_for() function efficiently (its behavior is clearly "Future" like, and normally would require to introduce an expensive Future wrapper around all native couroutines, like upstream asyncio does). py/objgenerator: pend_throw: Return previous pended value. This effectively allows to store an additional value (not necessary an exception) in a coroutine while it's not being executed. uasyncio has exactly this usecase: to mark a coro waiting in I/O queue (and thus not executed in the normal scheduling queue), for the purpose of implementing wait_for() function (cancellation of such waiting coro by a timeout). 2017-10-21 11:13:44 +02:00			`0`
			`1`
			`raised ValueError()`
			`ret was: None`
py/objgenerator: Allow pend_throw to an unstarted generator. Replace the is_running field with a tri-state variable to indicate running/not-running/pending-exception. Update tests to cover the various cases. This allows cancellation in uasyncio even if the coroutine hasn't been executed yet. Fixes #5242 2019-10-29 11:04:55 +01:00			`raised OSError()`
			`raised ValueError('generator already executing',)`
			`raised ValueError('generator already executing',)`
			`0`
			`ignore CancelledError`
			`1`
			`raised CancelledError()`
			`None`
			`CancelledError()`
			`CancelledError()`
			`1`