Chapter 14 - Generics

Exercise 1

fn main() {
    let mut shopping_list: Vec<???> = Vec::new();
    shopping_list.push("milk");
}

Generic data type in Rust is used for create definations of items like for item of an array or vector.

fn main() {
    let mut shopping_list: Vec<&str> = Vec::new();
    shopping_list.push("milk");
}

Exercise 2

// This powerful wrapper provides the ability to store a positive integer value.
// Rewrite it using generics so that it supports wrapping ANY type.

struct Wrapper {
    value: u32,
}

impl Wrapper {
    pub fn new(value: u32) -> Self {
        Wrapper { value }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn store_u32_in_wrapper() {
        assert_eq!(Wrapper::new(42).value, 42);
    }

    #[test]
    fn store_str_in_wrapper() {
        assert_eq!(Wrapper::new("Foo").value, "Foo");
    }
}

https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-method-definitions
Just refactor the code to use generic type

struct Wrapper<T> {
    value: T,
}

impl<T> Wrapper<T> {
    pub fn new(value: T) -> Self {
        Wrapper { value }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn store_u32_in_wrapper() {
        assert_eq!(Wrapper::new(42).value, 42);
    }

    #[test]
    fn store_str_in_wrapper() {
        assert_eq!(Wrapper::new("Foo").value, "Foo");
    }
}

Conclusion

The 14th chapter of Rustlings - Generics ends here.
TIL:

How to use generic type in Rust

Thanks for reading and please add comments below if you have any questions