totechite · May 17, 2023 02:33 · Oct 3, 2018 · Oct 3, 2018 · Oct 3, 2018 · Oct 3, 2018
diff --git a/move_semantics3.rs b/move_semantics3.rs
@@ -6,7 +6,7 @@
 pub fn main() {
     let vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0.clone());
+    let mut vec1 = fill_vec(vec0);
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 

diff --git a/move_semantics1.rs b/move_semantics1.rs
@@ -6,7 +6,7 @@ pub fn main() {
 
     let mut vec1 = fill_vec(vec0);
 
-    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), &vec1);
+    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
     vec1.push(88);
 

diff --git a/move_semantics3.rs b/move_semantics3.rs
@@ -0,0 +1,46 @@
+// move_semantics3.rs
+// Make me compile without adding new lines-- just changing existing lines!
+// (no lines with multiple semicolons necessary!)
+// Scroll down for hints :)
+
+pub fn main() {
+    let vec0 = Vec::new();
+
+    let mut vec1 = fill_vec(vec0.clone());
+
+    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
+
+    vec1.push(88);
+
+    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
+
+}
+
+fn fill_vec(mut vec: Vec<i32>) -> Vec<i32> {
+    vec.push(22);
+    vec.push(44);
+    vec.push(66);
+
+    vec
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// The difference between this one and the previous ones is that the first line
+// of `fn fill_vec` that had `let mut vec = vec;` is no longer there. You can,
+// instead of adding that line back, add `mut` in one place that will change
+// an existing binding to be a mutable binding instead of an immutable one :)
diff --git a/move_semantics4.rs b/move_semantics4.rs
@@ -0,0 +1,43 @@
+// move_semantics4.rs
+// Refactor this code so that instead of having `vec0` and creating the vector
+// in `fn main`, we instead create it within `fn fill_vec` and transfer the
+// freshly created vector from fill_vec to its caller. Scroll for hints!
+
+pub fn main() {
+
+    let mut vec1 = fill_vec();
+
+    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
+
+    vec1.push(88);
+
+    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
+
+}
+
+fn fill_vec() -> Vec<i32> {
+    [22, 44, 66].to_vec()
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// Stop reading whenever you feel like you have enough direction :) Or try
+// doing one step and then fixing the compiler errors that result!
+// So the end goal is to:
+// - get rid of the first line in main that creates the new vector
+// - so then `vec0` doesn't exist, so we can't pass it to `fill_vec`
+// - we don't want to pass anything to `fill_vec`, so its signature should
+//   reflect that it does not take any arguments
+// - since we're not creating a new vec in `main` anymore, we need to create
+//   a new vec in `fill_vec`, similarly to the way we did in `main`
diff --git a/move_semantics1.rs b/move_semantics1.rs
@@ -0,0 +1,43 @@
+// move_semantics1.rs
+// Make me compile! Scroll down for hints :)
+
+pub fn main() {
+    let vec0 = Vec::new();
+
+    let mut vec1 = fill_vec(vec0);
+
+    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), &vec1);
+
+    vec1.push(88);
+
+    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
+
+}
+
+fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+    let mut vec = vec;
+
+    vec.push(22);
+    vec.push(44);
+    vec.push(66);
+
+    vec
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// So you've got the "cannot borrow immutable local variable `vec1` as mutable" error on line 11,
+// right? The fix for this is going to be adding one keyword, and the addition is NOT on line 11
+// where the error is.
diff --git a/move_semantics2-1.rs b/move_semantics2-1.rs
@@ -0,0 +1,54 @@
+// move_semantics2.rs
+// Make me compile without changing line 10! Scroll down for hints :)
+
+pub fn main() {
+    let vec0 = Vec::new();
+
+    let mut vec1 = fill_vec(vec0.clone());
+
+    // Do not change the following line!
+    println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);
+
+    vec1.push(88);
+
+    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
+
+}
+
+fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+    let mut vec = vec;
+
+    vec.push(22);
+    vec.push(44);
+    vec.push(66);
+
+    vec
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// So `vec0` is being *moved* into the function `fill_vec` when we call it on
+// line 7, which means it gets dropped at the end of `fill_vec`, which means we
+// can't use `vec0` again on line 10 (or anywhere else in `main` after the
+// `fill_vec` call for that matter). We could fix this in a few ways, try them
+// all!
+// 1. Make another, separate version of the data that's in `vec0` and pass that
+// to `fill_vec` instead.
+// 2. Make `fill_vec` borrow its argument instead of taking ownership of it,
+// and then copy the data within the function in order to return an owned
+// `Vec<i32>`
+// 3. Make `fill_vec` *mutably* borrow its argument (which will need to be
+// mutable), modify it directly, then not return anything. Then you can get rid
+// of `vec1` entirely -- note that this will change what gets printed by the
+// first `println!`
diff --git a/move_semantics2-2.rs b/move_semantics2-2.rs
@@ -0,0 +1,54 @@
+// move_semantics2.rs
+// Make me compile without changing line 10! Scroll down for hints :)
+
+pub fn main() {
+    let vec0 = Vec::new();
+
+    let mut vec1 = fill_vec(&vec0);
+
+    // Do not change the following line!
+    println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);
+
+    vec1.push(88);
+
+    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
+
+}
+
+fn fill_vec(vec: &Vec<i32>) -> Vec<i32> {
+    let mut vec = vec.clone();
+
+    vec.push(22);
+    vec.push(44);
+    vec.push(66);
+
+    vec
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// So `vec0` is being *moved* into the function `fill_vec` when we call it on
+// line 7, which means it gets dropped at the end of `fill_vec`, which means we
+// can't use `vec0` again on line 10 (or anywhere else in `main` after the
+// `fill_vec` call for that matter). We could fix this in a few ways, try them
+// all!
+// 1. Make another, separate version of the data that's in `vec0` and pass that
+// to `fill_vec` instead.
+// 2. Make `fill_vec` borrow its argument instead of taking ownership of it,
+// and then copy the data within the function in order to return an owned
+// `Vec<i32>`
+// 3. Make `fill_vec` *mutably* borrow its argument (which will need to be
+// mutable), modify it directly, then not return anything. Then you can get rid
+// of `vec1` entirely -- note that this will change what gets printed by the
+// first `println!`
diff --git a/move_semantics2-3.rs b/move_semantics2-3.rs
@@ -0,0 +1,49 @@
+// move_semantics2.rs
+// Make me compile without changing line 10! Scroll down for hints :)
+
+pub fn main() {
+    let mut vec0 = Vec::new();
+
+    fill_vec(&mut vec0);
+
+    // Do not change the following line!
+    println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);
+
+}
+
+fn fill_vec(vec: &mut Vec<i32>) {
+    let vec = vec;
+
+    vec.push(22);
+    vec.push(44);
+    vec.push(66);
+
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+// So `vec0` is being *moved* into the function `fill_vec` when we call it on
+// line 7, which means it gets dropped at the end of `fill_vec`, which means we
+// can't use `vec0` again on line 10 (or anywhere else in `main` after the
+// `fill_vec` call for that matter). We could fix this in a few ways, try them
+// all!
+// 1. Make another, separate version of the data that's in `vec0` and pass that
+// to `fill_vec` instead.
+// 2. Make `fill_vec` borrow its argument instead of taking ownership of it,
+// and then copy the data within the function in order to return an owned
+// `Vec<i32>`
+// 3. Make `fill_vec` *mutably* borrow its argument (which will need to be
+// mutable), modify it directly, then not return anything. Then you can get rid
+// of `vec1` entirely -- note that this will change what gets printed by the
+// first `println!`