some iterator tuning

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

diff --git a/workspace/src/part05.rs b/workspace/src/part05.rs
index a2da18f2a435b8fe66595de2fecad8aed74ec87b..78113b7bb36e5e5acc1af45842f66e6de153ceb2 100644 (file)
--- a/workspace/src/part05.rs
+++ b/workspace/src/part05.rs
@@ -4,14 +4,14 @@
 // ## Big Numbers
 
 pub struct BigInt {
 // ## 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 {
 }
 
 // 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!()
         }
         } else {
             unimplemented!()
         }


@@ -31,7 +31,7 @@ impl BigInt {
     // 
     // **Exercise 05.1**: Implement this function.
     // 
     // 
     // **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!()
     }
     pub fn from_vec(mut v: Vec<u64>) -> Self {
         unimplemented!()
     }


@@ -59,7 +59,7 @@ 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
 }
 
 // **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?
+// digits? The number of non-zero digits? The smallest/largest digit? Of course, these should all just borrow `self`.

 
 // ## Mutation + aliasing considered harmful (part 2)
 enum Variant {
 
 // ## Mutation + aliasing considered harmful (part 2)
 enum Variant {


@@ -72,7 +72,7 @@ fn work_on_variant(mut var: Variant, text: String) {
         Variant::Number(ref mut n) => ptr = n,
         Variant::Text(_) => return,
     }
         Variant::Number(ref mut n) => ptr = n,
         Variant::Text(_) => return,
     }

-    /* var = Variant::Text(text); */
+    /* var = Variant::Text(text); */                                /* BAD! */

     *ptr = 1337;
 }
 
     *ptr = 1337;
 }