我需要处理来自外部Rust crate的枚举，它包含不同的数据类型：

pub enum Variables {
    Float(f32),
    Double(f64)
}

字符串
我想将其转换为我自己的通用数据结构，并将其 Package 在一个不同的结构中，以使用元数据丰富它：

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct MyWrapperVar<T> {
    num: i8,
    id: String,
    var: MyVar<T>,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct MyVar<T> {
    name: String,
    value: T,
}

型
MyWrapperVar的序列化将被序列化并发送给不同的消费者。为了便于序列化，我创建了多个new函数：

impl MyVar<f32> {
    fn new(name: &str, value: f32) -> Self {
        Self {
            name: name.to_string(),
            value,
        }
    }
}

impl MyVar<f64> {
    fn new(name: &str, value: f64) -> Self {
        Self {
            name: name.to_string(),
            value,
        }
    }
}

impl<T> MyWrapperVar<T> {
    fn new(
        num: i8,
        id: &str,
        variable_name: &str,
        variable_value: T,
    ) -> MyWrapperVar<T> {
        Self {
            num,
            id: id.to_string(),
            var: MyVar::<T>::new(variable_name, variable_value),
        }
    }
}

型
我的印象是，我可以简单地匹配Variables，然后调用我的通用MyWrapperVar::new函数：

fn main() {
    let var1 = Variables::Float(0.1);
    match var1 {
        Variables::Float(v) => {
            let bla = MyWrapperVar::new(0, "bla", "var1", v);
        }
        Variables::Double(v) => {
            let bla = MyWrapperVar::new(0, "bla", "var1", v);
        }
    }
}

型
但是，这似乎不起作用，因为我得到以下错误：

error[E0599]: no function or associated item named `new` found for struct `MyVar<T>` in the current scope
  --> src/main.rs:42:30
   |
9  | pub struct MyVar<T> {
   | ------------------- function or associated item `new` not found for this struct
...
42 |             var: MyVar::<T>::new(variable_name, variable_value),
   |                              ^^^ function or associated item not found in `MyVar<T>`
   |
   = note: the function or associated item was found for
           - `MyVar<f32>`
           - `MyVar<f64>`

For more information about this error, try `rustc --explain E0599`.

型
参见Rust Playground以获取MRE。