the official term is mutable references, be more explicit about that

[rust-101.git] / workspace / src / part05.rs

diff --git a/workspace/src/part05.rs b/workspace/src/part05.rs
index 78113b7bb36e5e5acc1af45842f66e6de153ceb2..28c4030aef6f4200c77b983551c05a0ac0ef52ec 100644 (file)
--- a/workspace/src/part05.rs
+++ b/workspace/src/part05.rs
@@ -26,8 +26,10 @@ impl BigInt {
     }
 
     // We can convert any vector of digits into a number, by removing trailing zeros. The `mut`
-    // declaration for `v` here is just like the one in `let mut ...`, it says that we will locally
-    // change the vector `v`.
+    // declaration for `v` here is just like the one in `let mut ...`: We completely own `v`, but Rust
+    // still asks us to make our intention of modifying it explicit. This `mut` is *not* part of the
+    // type of `from_vec` - the caller has to give up ownership of `v` anyway, so they don't care anymore
+    // what you do to it.
     // 
     // **Exercise 05.1**: Implement this function.
     // 
@@ -59,7 +61,7 @@ impl<T: Clone> Clone for SomethingOrNothing<T> {
 }
 
 // **Exercise 05.2**: Write some more functions on `BigInt`. What about a function that returns the number of
-// digits? The number of non-zero digits? The smallest/largest digit? Of course, these should all just borrow `self`.
+// digits? The number of non-zero digits? The smallest/largest digit? Of course, these should all take `self` as a shared reference (i.e., in borrowed form).
 
 // ## Mutation + aliasing considered harmful (part 2)
 enum Variant {