vec_different_types

This is a playground showcasing 2 ways to create a vector holding elements of different types

Initial situation

Assume you have two structs Support and Bend that share common behaviours like having coordinates in space with the struct Coordinates.

struct Support {
    coordinates: Coordinates,
    // Other `Support` specific fields
}

struct Bend {
    coordinates: Coordinates,
    // Other `Bend` specific fields
}

struct Coordinates {
    x: f32,
    y: f32,
    z: f32,
}

In order to create a vector that can hold either type and access the shared behaviour we have the following two approaches.

Using Enum

Create a enum containing tuple-like variants.

enum NodeEnum {
    Support(Support),
    Bend(Bend),
}

Implement functions with desired behaviour via pattern matching for this enum

impl NodeEnum {
    fn coordinates(&self) -> Coordinates {
        match self {
            NodeEnum::Support(support) => support.coordinates.clone(),
            NodeEnum::Bend(bend) => bend.coordinates.clone(),
        }
    }
}

Create a vector of the type Vec<NodeEnum> and push elements

pub fn enum_vec() {
    let mut vec: Vec<NodeEnum> = Vec::new();
    vec.push(NodeEnum::Support(Support::default()));
    vec.push(NodeEnum::Bend(Bend::default()));

    println!("\nVector with Enum:\n");
    for element in vec {
        // Access shared behaviour
        println!("{:?}", element.coordinates())
    }
}

Using Trait

Create a trait NodeTrait with a prototype function of the desired behaviour

trait NodeTrait {
    fn coordinates(&self) -> Coordinates;
}

Implement the trait and functions with a body for the structs

impl NodeTrait for Support {
    fn coordinates(&self) -> Coordinates {
        self.coordinates.clone()
    }
}

impl NodeTrait for Bend {
    fn coordinates(&self) -> Coordinates {
        self.coordinates.clone()
    }
}

Create a vector of type Vec<Box<dyn Trait>> and push elements

pub fn trait_vec() {
    let mut vec: Vec<Box<dyn NodeTrait>> = Vec::new();
    vec.push(Box::new(Support::default()));
    vec.push(Box::new(Bend::default()));

    println!("\nVector with Box<dyn Trait>:\n");
    for element in vec {
        // Access shared behaviour
        println!("{:?}", element.coordinates())
    }
}