I have a few mathematical objects which I have mostly stripped down to illustrate my questions regarding the idiomatic design of such a collection. All of these objects share a few common variables, but some have additional ones. In this stripped down example, using these variables, I want to calculate function:

pub trait Function {
    function(&self, h: f64) -> f64;
}

// the mathematical objects
pub struct A {
    pub dim: usize,
    pub len: f64,
}

pub struct B {
    pub dim: usize,
    pub len: f64,
    pub a: f64
}
// and a few more similar structs would follow here

impl Function for A {
    fn function(&self, h: f64) -> f64 {
        h
    }
}
impl Function for B {
    fn function(&self, h: f64) -> f64 {
        h * self.a
    }
}

This works nicely so far, although I’m not sure, if it would be a better approach to put the common variables into some kind of “base struct” like this:

pub struct Base {
    pub dim: usize,
    pub len: f64
}
pub struct A {
    pub base: Base
}

pub struct B {
    pub base: Base
    pub a: f64
}

However, this wouldn’t really solve my next problem. Say I want to plot function and in order to determine the domain of the x-axis, I would need the variable len, like this for A:

pub fn plot(a: A) {
    // determine x-axis
    let x_max = a.len * 3.0;
    // e.g. plot `a.function` over 0.0..x_max
}

It seems to me, that I would have to implement the plot function for every single struct I have, because I cannot use a trait object, when I need additional data from a struct. And a function like plot(c: Box<dyn Function>, len: f64) (maybe also with static dispatch) seems clumsy, as at least I know (in contrast to the compiler) that the field Base.len will exist for every single case.

Basically, I want a type, which has the trait Function and which has a few fields, like in this case len. This sounds very OOP, which got me thinking that I might be taking a completely wrong approach.

What design should I use, to make this all idiomatic Rust and also to make it as general and convenient to use as possible?