Rust futures - 版本历史

Riguz：/* Unwrap */

2024-12-28T11:42:37Z

Unwrap

←上一版本		2024年12月28日 (六) 11:42的版本
第36行：		第36行：
	</syntaxhighlight>		</syntaxhighlight>

			You can set default value if unwrap failed, thus no panic:

			<syntaxhighlight lang="rust">
			let url1 = get_url(&google).unwrap_or_default();
			let url2 = get_url(&unknown).unwrap_or_default();
			let url3 = get_url(&unknown).unwrap_or(String::from("<Unknown url>"));
			println!("Url of {} is {}", google, url1);
			println!("Url of {} is {}", unknown, url2);
			println!("Url of {} is {}", unknown, url3);
			//Url of Google is https://google.com
			//Url of Unknown is
			//Url of Unknown is <Unknown url>
			</syntaxhighlight>

			`unwrap_or_else` accepts a function to convert error to result type:

			<syntaxhighlight lang="rust">
			let url2 = get_url(&unknown).unwrap_or_else(\|err\| format!("Unknown url, error code={}!", err));
			// Url of Unknown is Unknown url, error code=2!
			</syntaxhighlight>
	[[Category:Rust]]		[[Category:Rust]]

2024-12-28T11:36:41Z

Unwrap

←上一版本		2024年12月28日 (六) 11:36的版本
第10行：		第10行：
	}		}
	}		}
			</syntaxhighlight>

			You could unwarp the result of error by calling `unwrap` or `unwrap_err`,
			be aware that it will panic if not matched:

			<syntaxhighlight lang="rust">
	fn main() {		fn main() {
	let ~~site~~: String = String::from("Google");		let google: String = String::from("Google");
	let ~~url~~: String = get_url(&~~site~~).unwrap();		let unknown: String = String::from("Unknown");
	println!("Url of {} is {}", ~~site~~, url);
			let url = get_url(&google).unwrap();
			println!("Url of {} is {}", google, url);
	// Url of Google is https://google.com		// Url of Google is https://google.com
	}
	~~</syntaxhighlight>~~

	~~If result~~ is ~~Err~~, ~~then unwrap will panic:~~		// panic
			// let url = get_url(&unknown).unwrap();

			let err = get_url(&unknown).unwrap_err();
			println!("error code is {}", err);
			// error code is 2

	~~<syntaxhighlight lang="rust">~~		// panic
	~~fn main() {~~		//let err = get_url(&google).unwrap_err();
	~~let site: String = String::from("Unknown");~~
	let ~~url: String~~ = get_url(&~~site~~).~~unwrap~~();
	~~println!("Url of {} is {}", site, url);~~
	~~// thread 'main' panicked at src/main.rs:27:38:~~
	~~// called `Result::unwrap()` on an `Err` value: 2~~
	}		}
	</syntaxhighlight>		</syntaxhighlight>

	[[Category:Rust]]		[[Category:Rust]]

2024-12-28T11:31:12Z

Unwrap

←上一版本		2024年12月28日 (六) 11:31的版本
第20行：		第20行：

	If result is Err, then unwrap will panic:		If result is Err, then unwrap will panic:


	<syntaxhighlight lang="rust">		<syntaxhighlight lang="rust">

2024-12-28T11:31:00Z

←上一版本		2024年12月28日 (六) 11:31的版本
第17行：		第17行：
	// Url of Google is https://google.com		// Url of Google is https://google.com
	}		}
			</syntaxhighlight>

	~~</syntaxhighlight>~~		If result is Err, then unwrap will panic:


			<syntaxhighlight lang="rust">
			fn main() {
			let site: String = String::from("Unknown");
			let url: String = get_url(&site).unwrap();
			println!("Url of {} is {}", site, url);
			// thread 'main' panicked at src/main.rs:27:38:
			// called `Result::unwrap()` on an `Err` value: 2
			}
			</syntaxhighlight>
	[[Category:Rust]]		[[Category:Rust]]

2024-12-28T11:29:34Z

←上一版本		2024年12月28日 (六) 11:29的版本
第1行：		第1行：
			= Result =
			== Unwrap ==
			<syntaxhighlight lang="rust">
			fn get_url(name: &String) -> Result<String, i32> {
			match name.as_str() {
			"Google" => Ok(String::from("https://google.com")),
			"Bing" => Ok(String::from("https://bing.com")),
			"" => Err(1),
			_ => Err(2),
			}
			}

			fn main() {
			let site: String = String::from("Google");
			let url: String = get_url(&site).unwrap();
			println!("Url of {} is {}", site, url);
			// Url of Google is https://google.com
			}

			</syntaxhighlight>


	[[Category:Rust]]		[[Category:Rust]]

2024-12-28T11:20:36Z

创建页面，内容为“ Category:Rust”

新页面

[[Category:Rust]]