The newtype pattern with Deref/DerefMut trait implementation

newtype_pattern.rs

/*
    To implement a trait on a type, the trait or the type has to be local to the code you work on. It is called the orphan rule.
    To get around this restriction, we can use the newtype pattern which involves creating a new type in a tuple struct.
    Both Vec<T> and Display trait are from the standard library and neither is local to our code.
    We are not able to implement Display trait to Vec<T>. But we can construct a wrapper type holding an instance of Vec<T> and implement Display trait on it.
    In the following example, VecWrapper<T> struct wraps Vec<T> and implements Display trait.
    To get all the methods of Vec<T> available to VecWrapper, Deref trait is implemented on it.

    ref: https://doc.rust-lang.org/book/ch19-03-advanced-traits.html?search=borrow%20and%20asref
*/

use std::fmt::{Debug, Display, Formatter, Result};
use std::ops::{Deref, DerefMut};

fn main() {
    let mut v = VecWrapper::<i32>::new();
    v.push(1);
    v.push(2);
    v.push(3);

    println!("{}", v);
}

#[derive(Debug)]
pub struct VecWrapper<T>(Vec<T>);

impl<T: Debug> VecWrapper<T> {
    pub fn new() -> VecWrapper<T> {
        VecWrapper(Vec::<T>::new())
    }

    pub fn with_capacity(capacity: usize) -> VecWrapper<T> {
        VecWrapper(Vec::<T>::with_capacity(capacity))
    }
}

impl<T: Debug> Default for VecWrapper<T> {
    fn default() -> VecWrapper<T> {
        VecWrapper::new()
    }
}

impl<T: Debug> Display for VecWrapper<T> {
    fn fmt(&self, f: &mut Formatter) -> Result {
        write!(f, "{:?}", self.0)
    }
}

impl<T: Debug> Deref for VecWrapper<T> {
    type Target = Vec<T>;
    fn deref(&self) -> &Vec<T> {
        &self.0
    }
}

impl<T: Debug> DerefMut for VecWrapper<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}