Python 3.5+collectionsterm

collections.abc.AsyncIterator

collections.abc — protocols

The async iterator protocol: has __anext__ and __aiter__.

Syntax

isinstance(obj, collections.abc.AsyncIterator)

The isinstance check is structural: anything defining __anext__ and __aiter__ passes, no subclassing or registration needed, but only the presence of the methods is verified, never their behaviour. An async generator is single-pass, so once an async for has drained it, a second loop yields nothing. You rarely implement the protocol by hand — an async def with yield in it gives you one for free.

Examples

import collections.abc as abc
async def ag():
    yield 1
print(isinstance(ag(), abc.AsyncIterator))   # → True

See also

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