How to do it...

Follow these steps:

1. Open the Cargo.toml file that was generated earlier for you.

2. In the folder bin, create a file called raii.rs.

3. Add the following code and run it with cargo run --bin raii:

1   use std::ops::Deref;
2 
3   // This represents a low level, close to the metal OS feature 
     that
4   // needs to be locked and unlocked in some way in order to be   
     accessed
5   // and is usually unsafe to use directly
6   struct SomeOsSpecificFunctionalityHandle;
7 
8   // This is a safe wrapper around the low level struct
9   struct SomeOsFunctionality<T> {
10    // The data variable represents whatever useful information
11    // the user might provide to the OS functionality
12    data: T,
13    // The underlying struct is usually not savely movable,
14    // so it's given a constant address in a box
15    inner: Box<SomeOsSpecificFunctionalityHandle>,
16  }
17 
18  // Access to a locked SomeOsFunctionality is wrapped in a guard
19  // that automatically unlocks...