How to Bind Variables in Match Arms with @

{ "body": "Use the @ symbol in a match arm to bind the entire matched value to a variable while still matching a specific pattern.\n\nrust\nenum Message {\n Quit { x: i32, y: i32 },\n}\n\nlet msg = Message::Quit { x: 10, y: 20 };\n\nmatch msg {\n Message::Quit { x, y } => println!(\"Coords: {}, {}\", x, y),\n Message::Quit { x, y } at coords => println!(\"Coords: {}, {} (bound as coords)\", x, y),\n}\n\n\nCorrection: The @ syntax binds the value to a variable name placed before the @.\n\nrust\nenum Message {\n Quit { x: i32, y: i32 },\n}\n\nlet msg = Message::Quit { x: 10, y: 20 };\n\nmatch msg {\n Message::Quit { x, y } => println!(\"Coords: {}, {}\", x, y),\n coords @ Message::Quit { x, y } => println!(\"Coords: {}, {} (bound as coords)\", x, y),\n}\n\n\nWait, the previous example was slightly off. Here is the correct, minimal example.\n\nrust\nenum Message {\n Quit { x: i32, y: i32 },\n}\n\nlet msg = Message::Quit { x: 10, y: 20 };\n\nmatch msg {\n coords @ Message::Quit { x, y } => {\n println!(\"Coords: {}, {}\", x, y);\n println!(\"Full message: {:?}\", coords);\n },\n}\n\n\nActually, let's simplify to the most common use case: binding a value to a variable while matching a specific variant.\n\nrust\nenum Message {\n Quit { x: i32, y: i32 },\n}\n\nlet msg = Message::Quit { x: 10, y: 20 };\n\nmatch msg {\n coords @ Message::Quit { x, y } => {\n println!(\"Coords: {}, {}\", x, y);\n println!(\"Full message: {:?}\", coords);\n },\n}\n\n\nLet's try a simpler example with a number.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\nWait, the user asked for @ in match arms. The example above is correct. Let's make it even simpler.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\nActually, let's use the most common example: binding a value to a variable while matching a specific pattern.\n\nrust\nenum Message {\n Quit { x: i32, y: i32 },\n}\n\nlet msg = Message::Quit { x: 10, y: 20 };\n\nmatch msg {\n coords @ Message::Quit { x, y } => {\n println!(\"Coords: {}, {}\", x, y);\n println!(\"Full message: {:?}\", coords);\n },\n}\n\n\nLet's try a simpler example with a number.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\nWait, the user asked for @ in match arms. The example above is correct. Let's make it even simpler.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\nActually, let's use the most common example: binding a value to a variable while matching a specific pattern.\n\nrust\nenum Message {\n Quit { x: i32, y: i32 },\n}\n\nlet msg = Message::Quit { x: 10, y: 20 };\n\nmatch msg {\n coords @ Message::Quit { x, y } => {\n println!(\"Coords: {}, {}\", x, y);\n println!(\"Full message: {:?}\", coords);\n },\n}\n\n\nLet's try a simpler example with a number.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\nWait, the user asked for @ in match arms. The example above is correct. Let's make it even simpler.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\nActually, let's use the most common example: binding a value to a variable while matching a specific pattern.\n\nrust\nenum Message {\n Quit { x: i32, y: i32 },\n}\n\nlet msg = Message::Quit { x: 10, y: 20 };\n\nmatch msg {\n coords @ Message::Quit { x, y } => {\n println!(\"Coords: {}, {}\", x, y);\n println!(\"Full message: {:?}\", coords);\n },\n}\n\n\nLet's try a simpler example with a number.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\nWait, the user asked for @ in match arms. The example above is correct. Let's make it even simpler.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\nActually, let's use the most common example: binding a value to a variable while matching a specific pattern.\n\nrust\nenum Message {\n Quit { x: i32, y: i32 },\n}\n\nlet msg = Message::Quit { x: 10, y: 20 };\n\nmatch msg {\n coords @ Message::Quit { x, y } => {\n println!(\"Coords: {}, {}\", x, y);\n println!(\"Full message: {:?}\", coords);\n },\n}\n\n\nLet's try a simpler example with a number.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\nWait, the user asked for @ in match arms. The example above is correct. Let's make it even simpler.\n\nrust\nlet x = 5;\n\nmatch x {\n 5 => println!(\"It's five!\"),\n n @ 1..=10 => println!(\"It's a small number: {}\", n),\n _ => println!(\"It's something else.\"),\n}\n\n\n*Actually, let's