feat: improve fibonacci example

Author: 1995parham

fibonacci-1/src/fibonacci/mod.rs

@@ -0,0 +1,14 @@
+use crate::fibonacci::rec::Recursive;
+
+mod rec;
+
+pub trait Fibonacci {
+    fn fibonacci(&self, n: i32) -> i64;
+}
+
+pub fn choose(name: &str) -> Box<dyn Fibonacci> {
+    match name {
+        "recursive" => Box::new(Recursive {}),
+        _ => panic!("no such a fibonacci implementation named {}", name),
+    }
+}

fibonacci-1/src/fibonacci/rec.rs

@@ -0,0 +1,13 @@
+use crate::fibonacci::Fibonacci;
+
+pub struct Recursive {}
+
+impl Fibonacci for Recursive {
+    fn fibonacci(&self, n: i32) -> i64 {
+        if n == 0 || n == 1 {
+            1
+        } else {
+            self.fibonacci(n - 1) + self.fibonacci(n - 2)
+        }
+    }
+}

fibonacci-1/src/main.rs

@@ -1,11 +1,9 @@
-fn fibonacci(n: u64) -> u64 {
-    if n == 0 || n == 1 {
-        return 0;
-    } else {
-        fibonacci(n - 1) + fibonacci(n - 2)
-    }
-}
+use crate::fibonacci::choose;
+
+mod fibonacci;
 
 fn main() {
-    println!("{}", fibonacci(10));
+    let r = choose("recursive");
+
+    println!("{}", r.fibonacci(10));
 }