Python 3.6+collectionsterm

collections.abc.AsyncGenerator

collections.abc — protocols

The async generator protocol: an async iterator with asend/athrow/aclose.

Syntax

isinstance(obj, collections.abc.AsyncGenerator)

The check is structural: nothing has to inherit from the ABC, having __aiter__, __anext__, asend, athrow and aclose is enough, so a hand-rolled class with those methods passes too. The real gotcha is the object itself — calling ag() runs no code, the body only starts under async for inside a running event loop, and breaking out of that loop leaves finally blocks pending, so close it explicitly with aclose() or contextlib.aclosing.

Examples

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

See also

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