Rust Programming By Example

Hiding code blocks lines

If you want to use ?, you'll have to do it inside a function returning an Option or a Result. But still, inside a function. However, you don't necessarily want to show those lines to the user in order to focus on what you're trying to explain.

To put it simply, you just need to add a # at the beginning of the line. As simple as that. As always, let's show it with a small example:

/// ```
/// # fn foo() -> std::io::Result<()> {
/// let mut file = File::open("some-file.txt")?;
/// write!(file, "Hello world!")?;
/// # Ok(())
/// # }
/// ```

The user will only see the following:

let mut file = File::open("some-file.txt")?;
write!(file, "Hello world!")?;

However, if they click on the Run button, they'll see the following: ...