Implementing the Drop trait

Where traditional object-oriented languages have destructors, Rust has the Drop trait, which consists of a single drop function that is called whenever a variable's lifetime has ended. By implementing it, you can perform whatever cleanup or advanced logging is necessary. You can also automatically free resources via RAII, as we're going to see in the next recipe.

How to do it...

1. In the folder bin, create a file called drop.rs.

2. Add the following code and run it with cargo run --bin drop:

1   use std::fmt::Debug;
2 
3   struct CustomSmartPointer<D>
4   where
5   D: Debug,
6   {
7   data: D,
8   }
9 
10  impl<D> CustomSmartPointer<D>
11  where
12  D: Debug,
13  {
14    fn new(data: D) -> Self {
15    CustomSmartPointer { data }
16    }
17  }
18 
19  impl<D> Drop for CustomSmartPointer<D>
20  where
21  D: Debug,
22  {
23    // This will automatically be called when a variable is 
       dropped
24    // It cannot be called manually
25...