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move_semantics2 solution
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3 changed files with 35 additions and 14 deletions
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@ -1,5 +1,3 @@
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// Make the test pass by finding a way to keep both Vecs separate!
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fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
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fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
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let mut vec = vec;
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let mut vec = vec;
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@ -16,13 +14,15 @@ fn main() {
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mod tests {
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mod tests {
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use super::*;
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use super::*;
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// TODO: Make both vectors `vec0` and `vec1` accessible at the same time to
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// fix the compiler error in the test.
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#[test]
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#[test]
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fn move_semantics2() {
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fn move_semantics2() {
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let vec0 = vec![22, 44, 66];
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let vec0 = vec![22, 44, 66];
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let vec1 = fill_vec(vec0);
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let vec1 = fill_vec(vec0);
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assert_eq!(vec0, vec![22, 44, 66]);
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assert_eq!(vec0, [22, 44, 66]);
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assert_eq!(vec1, vec![22, 44, 66, 88]);
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assert_eq!(vec1, [22, 44, 66, 88]);
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}
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}
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}
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}
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@ -352,16 +352,10 @@ When running this exercise for the first time, you'll notice an error about
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"borrow of moved value". In Rust, when an argument is passed to a function and
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"borrow of moved value". In Rust, when an argument is passed to a function and
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it's not explicitly returned, you can't use the original variable anymore.
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it's not explicitly returned, you can't use the original variable anymore.
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We call this "moving" a variable. When we pass `vec0` into `fill_vec`, it's
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We call this "moving" a variable. When we pass `vec0` into `fill_vec`, it's
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being "moved" into `vec1`, meaning we can't access `vec0` anymore after the
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being "moved" into `vec1`, meaning we can't access `vec0` anymore.
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fact.
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Rust provides a couple of different ways to mitigate this issue, feel free to
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You could make another, separate version of the data that's in `vec0` and
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try them all:
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pass it to `fill_vec` instead.
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1. You could make another, separate version of the data that's in `vec0` and
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pass that to `fill_vec` instead.
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2. Make `fill_vec` borrow its argument instead of taking ownership of it,
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and then copy the data within the function (`vec.clone()`) in order to
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return an owned `Vec<i32>`.
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"""
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"""
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[[exercises]]
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[[exercises]]
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@ -1 +1,28 @@
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// Solutions will be available before the stable release. Thank you for testing the beta version 🥰
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fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
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let mut vec = vec;
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vec.push(88);
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vec
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}
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fn main() {
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// You can optionally experiment here.
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn move_semantics2() {
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let vec0 = vec![22, 44, 66];
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// Cloning `vec0` so that the clone is moved into `fill_vec`, not `vec0`
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// itself.
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let vec1 = fill_vec(vec0.clone());
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assert_eq!(vec0, [22, 44, 66]);
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assert_eq!(vec1, [22, 44, 66, 88]);
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}
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}
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