René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Suggestion: Add more examples for “Type Hinting Asynchronous Objects” section in chapter 21 ","articleBody":"Dear Ramalho,\r\n\r\nI hope you are well. I'm writing to suggest an improvement for the “Type Hinting Asynchronous Objects” section in Chapter 21 for the next edition.\r\n\r\n**Enhancing Clarity with Examples**\r\n\r\nI believe that including additional examples in this section would significantly enhance understanding of how to properly use type hints for asynchronous objects. Here are some specific suggestions:\r\n\r\n* **Coroutines Example:**  A beneficial addition would be an example demonstrating type hints for coroutines.  The following code showcases how to achieve this:\r\n\r\n```python\r\nimport asyncio\r\nimport socket\r\n\r\nfrom collections.abc import AsyncGenerator, Generator, Coroutine, Callable\r\n\r\n\r\ndef get_ipv4_by_hostname(hostname: str) -\u003e list[str]:\r\n    return list(\r\n        i[4][0]\r\n        for i in \r\n        socket.getaddrinfo(hostname, 0)\r\n        if i[0] is socket.AddressFamily.AF_INET\r\n        and i[1] is socket.SocketKind.SOCK_RAW  \r\n    )\r\n\r\n\r\nasync def get_ipv4_by_hostname_async(hostname: str) -\u003e list[str]:\r\n    return await asyncio.to_thread(get_ipv4_by_hostname, hostname)\r\n\r\n\r\nasync def print_domanin_ip(\r\n        domain: str,\r\n        get_ip: Callable[[str], Coroutine[None, None, list[str]]]) -\u003e None:\r\n    ips = await get_ip(domain)\r\n    if ips:\r\n        for ip in ips:\r\n            print(f'{domain}: {ip}')\r\n    else:\r\n        print(f'{domain}: No IP found')\r\n    print('_' * 20)\r\n\r\n\r\nasync def main() -\u003e None:\r\n    await print_domanin_ip('docker.com', get_ipv4_by_hostname_async)\r\n```\r\n\r\n* **AsyncGenerators Example:**  The official typing documentation provides an excellent and clear example for AsyncGenerators.  Including a similar example in the book would be valuable:\r\n\r\n```python\r\n\r\nasync def echo_round() -\u003e AsyncGenerator[int, float]:\r\n    sent = yield 0\r\n    while sent \u003e= 0.0:\r\n        rounded = await round(sent)\r\n        sent = yield rounded\r\n```\r\n\r\nI also guess that there might be a typo on the page 825, the image is provided below:\r\n![typo](https://github.com/fluentpython/example-code-2e/assets/17600026/8ccb1f53-b57c-4653-83bf-789d952cca4a)\r\n\r\nI think “to last” phrase should be removed because `Coroutine` is actually covariant on the third parameter.\r\n","author":{"url":"https://github.com/kamalfarahani","@type":"Person","name":"kamalfarahani"},"datePublished":"2024-05-05T17:29:06.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/44/example-code-2e/issues/44"}