Add a bunch of code

Signed-off-by: Carlos Maiolino <[email protected]>

1 files changed, 74 insertions, 0 deletions

diff --git a/rust/ownership.rs b/rust/ownership.rs
new file mode 100644
index 0000000..3a96743
--- /dev/null
+++ b/rust/ownership.rs
@@ -0,0 +1,74 @@
+// Rules of ownership:
+//
+// 1 - each value has an owner
+// 2 - only one owner allowed
+// 3 - if owner goes out of scope, value will be freed
+//
+// Scopes: Global, local -> Similar to C
+
+fn main() -> () {
+
+    let h = "Hello"; // s is the owner
+    let s = get_string();
+
+//  let s2 = s;     // This only copies the pointer value, not the
+                    // String data type
+                    //
+                    // This essentially violates the ownership rule of
+                    // a single owner.
+                    // Because of that, rust compiler drops the ownership
+                    // of the original variable 's', only s2 owns the pointer
+                    // now.
+
+    let s2 = s.clone(); // Deep copy String s
+
+    println!("{}", h);
+
+    println!("{}", s2);
+
+    println!("{}", s);  // generates an error due to ownership if .clone ain't used
+
+
+    // Transferring ownership
+
+    take_ownership(s);  // 's' value is moved to the function. From now on, 's' is
+                        // no longer valid here.
+
+//  println!("{}", s); // KABOOM
+
+    // give_ownership allocate and return us a
+    // String type, giving s3 ownership of the
+    // allocated String.
+    // s3 belongs to this scope now.
+    let s3 = give_ownership();
+
+    // Sending and getting ownership back
+
+    let s5 = String::from("This is mine");
+    let s5 = give_me_back(s5);  // I'm shadowing s5 here, but I could have used
+                                // something else
+
+    println!("{} {}", s3, s5);
+
+} // s - only valid to here
+
+fn give_me_back(s: String) -> String {
+
+    return s;
+}
+
+fn give_ownership() -> String {
+
+    // The ownership of the String allocated here
+    // will be transferred to the caller.
+    return String::from("Jumento celestino");
+}
+fn take_ownership(s: String) {
+    println!("Ownership transfer completed. \n{}", s);
+
+    // Reaching end of this scope will free 's'
+}
+
+fn get_string() -> String {
+    return String::from("Ronaldo");
+}