X-Git-Url: https://git.ralfj.de/rust-101.git/blobdiff_plain/ff4d137ae8e7a6f126d845084009ebdfc990aa47..e7d7a4a73b044faa7f3959b9c48e1919bef0d54e:/workspace/src/part05.rs

diff --git a/workspace/src/part05.rs b/workspace/src/part05.rs
index f1c5587..65f6f7d 100644
--- a/workspace/src/part05.rs
+++ b/workspace/src/part05.rs
@@ -4,14 +4,14 @@
 // ## Big Numbers
 
 pub struct BigInt {
-    pub data: Vec<u64>,
+    pub data: Vec<u64>, // least significant digit first, no trailing zeros
 }
 
 // Now that we fixed the data representation, we can start implementing methods on it.
 impl BigInt {
     pub fn new(x: u64) -> Self {
         if x == 0 {
-            BigInt { data: vec![] }
+            unimplemented!()
         } else {
             unimplemented!()
         }
@@ -26,12 +26,14 @@ 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.
     // 
-    // *Hint*: You can use `pop()` to remove the last element of a vector.
+    // *Hint*: You can use `pop` to remove the last element of a vector.
     pub fn from_vec(mut v: Vec<u64>) -> Self {
         unimplemented!()
     }