Methods of Enums

What Are Methods? Just like structs, methods are functions specific to enums.
Syntax

To define methods of enum write the functions within the impl followed by the enum name and then the functions within the impl block.

Move enum related logic in the impl construct
Example The example below declares an enum, named TrafficSignal and defines an enum method is_stop within the impl construct:

#![allow(dead_code)]
#[derive(Debug)]
// declare an enum
enum TrafficSignal{
  Red, Green, Yellow
}
//implement a Traffic Signal methods
impl TrafficSignal{
  // if the signal is red then return
   fn is_stop(&self)->bool{
     match self{
       TrafficSignal::Red=>return true,
       _=>return false
     }
   }
}
fn main(){
  // define an enum instance
  let action = TrafficSignal::Red;
  //print the value of action
  println!("What is the signal value? - {:?}", action);
  //invoke the enum method 'is_stop' and print the value
  println!("Do we have to stop at signal? - {}", action.is_stop());
}

Output

What is the signal value? - Red
Do we have to stop at signal? - true

Quiz

Test your understanding of methods of enum in Rust.

What is the output of the following code?

#![allow(dead_code)]
#[derive(Debug)]
enum TrafficSignal {
  Red, Green, Yellow
}
impl TrafficSignal{
   fn is_stop(&self)->bool{
     match self{
       &TrafficSignal::Red=>return true,
       _=>return false
     }
   }
}
fn main(){
  let action = TrafficSignal::Yellow;
  println!("What is the signal value? - {:?}", action);
  println!("Do we have to stop at signal? - {}", action.is_stop());
}

What is the signal value? - Yellow
Do we have to stop at signal? - false

What is the signal value? - Red
Do we have to stop at signal? - true