Rust 将两个不同的结构体视为一个

Question

I have two different structs with similar functions. Suppose that the program choose which struct to take from the user input. I want to write something like this

fn main() {
   ... 
   let obj = if a == first {
       first_object //struct First
   } else {
       second_object//struct Second
   };
   
   obj.read();
   obj.write();
   obj.some_another_method();
}

I have tried to make an enumeration

pub enum ObjectKind {
    FirstObject(First),
    SecondObject(Second)
}

But I cannot use methods in this case

let something = ObjectKind::FirstObject(first_object);
something.read()

//no method named `read` found for enum `structs::ObjectKind` in the current scope
//method not found in `structs::ObjectKind`

Answer 1

But I cannot use methods in this case

An enum is a proper type in and of itself, it's not a "union" of existing types. You can just define the methods on the enum to forward to the relevant object eg

impl ObjectKind {
    fn read(&self) {
        match self {
            FirstObject(f) => f.read()
            SecondObject(s) => s.read()
        }
    }
}

as it would probably be a bit repetitive, you can use a macro to make the forwarding easier.

Alternatively, you might be able to define a trait for the common behaviour and use a trait object to dynamically dispatch between the two, but that can be somewhat restrictive.