with — Expert Examples

Wraps a block with a context manager for automatic setup/teardown

EasyIntermediateAdvancedExpert

Async context managers

Using 'async with' for async resource management.

python
import asyncio

class AsyncConnection:
    def __init__(self, name):
        self.name = name

    async def __aenter__(self):
        print(f"Async connecting to {self.name}")
        await asyncio.sleep(0)
        return self

    async def __aexit__(self, *args):
        print(f"Async disconnecting from {self.name}")
        await asyncio.sleep(0)

async def main():
    async with AsyncConnection("database") as conn:
        print(f"Using {conn.name}")

asyncio.run(main)

# Bytecode comparison
import dis
def sync_ctx():
    with open("x"): pass

print("\nWith statement bytecode:")
dis.dis(sync_ctx)

async with uses __aenter__ and __aexit__ for async setup/teardown. The bytecode uses BEFORE_ASYNC_WITH instead of BEFORE_WITH.

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