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This post is auto-generated from RSS feed The Rust Programming Language Forum - Latest topics. Source: Implement struct methods to do something on specific field

Hello, I have the following situation, that is best explained with the code below.

I have a struct with multiple similar fields, that I need to modify by calling a kind-of-setter method that calls other methods implemented on the struct.
This single setter method should modify the given field, however as I also require other methods implemented on the struct, I need to parse the struct instance as well as the reference to the field.

This doesn't work in Rust because now I have multiple mutable references to basically the same variable.

struct SomeStruct {
    a: u8,
    y: u8,
    foo: u64
};

impl SomeStruct {
    fn i_need_to_call_this(&mut self) {
        self.foo = 0;
    }

    fn write_to_field(&mut self, reference_to_field: &mut u8) {
        self.i_need_to_call_this();
        *reference_to_field = 42;
    }
}

fn main() {
    let mut this_struct: SomeStruct = SomeStruct { a:0, y: 1, foo: 2 };
    // These two will fail
    this_struct.write_to_field(&mut this_struct.a);
    this_struct.write_to_field(&mut this_struct.y);
}

I found this solution (How to pass a field name of a struct to a method of that struct? - #2 by jofas) that uses an enum representing the fields to choose between them.
However this requires that I remember to also update the enum when making changes (removing / adding fields) to the struct.

Are there other solutions that I'm not considering?
*reference_to_field = 42; would work if I don't pass the reference to the struct instance along, however I need that to call the i_need_to_call_this method ...

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