developed at FriendFeed. By using non-blocking network I/O, Tornado can scale to tens of thousands of open connections, making it ideal for long polling, WebSockets, and other applications that require a long-lived CONTENTSCHAPTER ONE QUICK LINKS • Current version: 6.5.1 (download from PyPI, release notes) • Source (GitHub) • Mailing lists: discussion and announcements • Stack Overflow • Wiki 3Tornado Documentation with pip. Note that the source distribution includes demo applications that are not present when Tornado is installed in this way, so you may wish to download a copy of the source tarball or clone the git

org/wiki/FriendFeed]. By using non-blocking network I/O, Tornado can scale to tens of thousands of open connections, making it ideal for long polling [https://en.wikipedia.org/wiki/Push_technology#Long_polling] Current version: 6.5.1 (download from PyPI [https://pypi.python.org/pypi/tornado], release notes) Source (GitHub) [https://github.com/tornadoweb/tornado] Mailing lists: discussion [https://groups.google with pip. Note that the source distribution includes demo applications that are not present when Tornado is installed in this way, so you may wish to download a copy of the source tarball or clone the git

中调用哪个方法，因 此每个 crate 有使用说明文档。Cargo 的另一个很棒的功能是运行 cargo doc --open 命令来构建所有本地依赖提供的文档并在浏览器中打开。例如，假设你对 rand crate 中的其他功能感兴趣，你可以运行 cargo doc --open 并点击左侧导航栏中的 rand。 新增加的第二行代码打印出了秘密数字。这在开发程序时很有用，因为可以测试它，不过在最 greeting_file_result = File::open("hello.txt"); } 示例 9-3：打开文件 File::open 的返回值是 Result。泛型参数 T 会被 File::open 的实现放入成功返回值的 类型 std::fs::File，这是一个文件句柄。错误返回值使用的 E 的类型是 std::io::Error。这 些返回类型意味着 File::open 调用可能成功并返回一个可以读写的文件句柄。这个函数调用 调用可能成功并返回一个可以读写的文件句柄。这个函数调用 也可能会失败：例如，也许文件不存在，或者可能没有权限访问这个文件。File::open 函数 需要一个方法在告诉我们成功与否的同时返回文件句柄或者错误信息。这些信息正好是 Result 枚举所代表的。 当 File::open 成功时，greeting_file_result 变量将会是一个包含文件句柄的 Ok 实例。当失 败时，greeting_file_result