sys.set_coroutine_wrapper()

sys.set_coroutine_wrapper(wrapper)

Allows intercepting creation of coroutine objects (only ones that are created by an async def function; generators decorated with types.coroutine() or asyncio.coroutine() will not be intercepted).

The wrapper argument must be either:

  • a callable that accepts one argument (a coroutine object);
  • None, to reset the wrapper.

If called twice, the new wrapper replaces the previous one. The function is thread-specific.

The wrapper callable cannot define new coroutines directly or indirectly:

def wrapper(coro):
    async def wrap(coro):
        return await coro
    return wrap(coro)
sys.set_coroutine_wrapper(wrapper)

async def foo():
    pass

# The following line will fail with a RuntimeError, because
# ``wrapper`` creates a ``wrap(coro)`` coroutine:
foo()

See also get_coroutine_wrapper().

New in version 3.5: See PEP 492 for more details.

Note

This function has been added on a provisional basis (see PEP 411 for details.) Use it only for debugging purposes.

doc_python
2016-10-07 17:43:58
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