强类型枚举作为rust中的联合:如何确定值的类型并检索它；如何做“构造函数”

enum Value {
    Integer(i32),
    Float(f64),
    Text(String),
}

fn main() {
    let value = Value::Integer(42);

    match value {
        Value::Integer(i) => println!("Integer: {}", i),
        Value::Float(f) => println!("Float: {}", f),
        Value::Text(s) => println!("Text: {}", s),
    }
}

fn main() {
    let value = Value::Float(3.14);

    if let Value::Float(f) = value {
        println!("Float: {}", f);
    } else {
        println!("Not a float");
    }
}

enum Value {
    Integer(i32),
    Float(f64),
    Text(String),
}

impl Value {
    fn new_integer(value: i32) -> Value {
        Value::Integer(value)
    }

    fn new_float(value: f64) -> Value {
        Value::Float(value)
    }

    fn new_text(value: String) -> Value {
        Value::Text(value)
    }
}

fn main() {
    let value = Value::new_integer(42);
}