Macro input 

macro_rules! input {
    () => { ... };
    ($($arg:tt)*) => { ... };
}

A macro that:

• optionally prints a prompt (with print!).
• reads one line from stdin.
• returns Err(InputError::Eof) if EOF is encountered.
• returns Err(InputError::Parse(e)) if the input cannot be parsed.
• returns Err(InputError::Io(e)) if an IO error occurs.

Usage:

// No prompt
let text: String = input!().unwrap();

// With prompt
let name: String = input!("Enter your name: ").unwrap();

// Formatted prompt
let user = "Alice";
let age: String = input!("Enter {}'s age: ", user).unwrap();