Code shared from the Rust Playground

immutable_and_mutable_tip.rs

pub struct Monster {
    hp: u8, // health points
    sp: u8, // spell points
    friends: Vec<Friend>,
}

pub struct Friend {
    loyalty: u8,
}

impl Monster {
    pub fn final_breath(&mut self) {
    
        // Error 
        // if let Some(friend) = self.friends.first() {
        
        //     self.heal(friend.loyalty);
        //     println!("Healing for {}", friend.loyalty);
            
        // }
    
        self.change_heal();
        self.display_heal();
        
       
    }
    
    
    fn change_heal(&mut self){
        if let Some(friend) = self.friends.first() {
        
            self.heal(friend.loyalty);
            
        }
    }
    
    
    fn display_heal(&self){
        if let Some(friend) = self.friends.first() {
            
            println!("Healing for {}", friend.loyalty);
            
        }
    }

    fn heal(&mut self, amount: u8) {
        self.hp += amount;
        self.sp -= amount;
    }
}

fn main() {}