X-Git-Url: https://git.ralfj.de/rust-101.git/blobdiff_plain/c25f3400060ea1a02f8fa9de69c39fd7b020e8a5..85f1f88dad52d7679bf5c1a5f5f6ab8d55252c33:/src/part07.rs?ds=sidebyside diff --git a/src/part07.rs b/src/part07.rs index 618eb22..2d88390 100644 --- a/src/part07.rs +++ b/src/part07.rs @@ -4,8 +4,8 @@ pub use part05::BigInt; // With our new knowledge of lifetimes, we are now able to write down the desired type of `min`: -//@ We want the function to take two borrows *of the same lifetime*, and then -//@ return a borrow of that lifetime. If the two input lifetimes would be different, we +//@ We want the function to take two references *with the same lifetime*, and then +//@ return a reference with that lifetime. If the two input lifetimes would be different, we //@ would not know which lifetime to use for the result. pub trait Minimum { fn min<'a>(&'a self, other: &'a Self) -> &'a Self; @@ -17,10 +17,10 @@ pub trait Minimum { pub fn vec_min(v: &Vec) -> Option<&T> { let mut min: Option<&T> = None; for e in v { - min = Some(match min { /*@*/ - None => e, /*@*/ - Some(n) => n.min(e) /*@*/ - }); /*@*/ + min = Some(match min { + None => e, + Some(n) => n.min(e) + }); } min } @@ -35,7 +35,7 @@ pub fn vec_min(v: &Vec) -> Option<&T> { // **Exercise 07.1**: For our `vec_min` to be usable with `BigInt`, you will have to provide an implementation of // `Minimum`. You should be able to pretty much copy the code you wrote for exercise 06.1. You should *not* -// make any copies! +// make any copies of `BigInt`! impl Minimum for BigInt { fn min<'a>(&'a self, other: &'a Self) -> &'a Self { unimplemented!() @@ -62,16 +62,16 @@ impl PartialEq for BigInt { //@ Since implementing `PartialEq` is a fairly mechanical business, you can let Rust automate this //@ by adding the attribute `derive(PartialEq)` to the type definition. In case you wonder about -//@ the "partial", I suggest you check out the documentation of [`PartialEq`](http://doc.rust-lang.org/std/cmp/trait.PartialEq.html) -//@ and [`Eq`](http://doc.rust-lang.org/std/cmp/trait.Eq.html). `Eq` can be automatically derived as well. +//@ the "partial", I suggest you check out the documentation of [`PartialEq`](https://doc.rust-lang.org/std/cmp/trait.PartialEq.html) +//@ and [`Eq`](https://doc.rust-lang.org/std/cmp/trait.Eq.html). `Eq` can be automatically derived as well. -// Now we can compare `BigInt`s. Rust treats `PratialEq` special in that it is wired to the operator `==`: -//@ That operator can not be used on our numbers! Speaking in C++ terms, we just overloaded the `==` operator +// Now we can compare `BigInt`s. Rust treats `PartialEq` special in that it is wired to the operator `==`: +//@ That operator can now be used on our numbers! Speaking in C++ terms, we just overloaded the `==` operator //@ for `BigInt`. Rust does not have function overloading (i.e., it will not dispatch to different //@ functions depending on the type of the argument). Instead, one typically finds (or defines) a //@ trait that catches the core characteristic common to all the overloads, and writes a single //@ function that's generic in the trait. For example, instead of overloading a function for all -//@ the ways a string can be represented, one writes a generic functions over [ToString](http://doc.rust-lang.org/std/string/trait.ToString.html). +//@ the ways a string can be represented, one writes a generic functions over [ToString](https://doc.rust-lang.org/std/string/trait.ToString.html). //@ Usually, there is a trait like this that fits the purpose - and if there is, this has the great //@ advantage that any type *you* write, that can convert to a string, just has to implement //@ that trait to be immediately usable with all the functions out there that generalize over `ToString`. @@ -113,7 +113,7 @@ fn test_min() { //@ that users can understand, while `Debug` is meant to show the internal state of data and targeted at //@ the programmer. The latter is what we want for `assert_eq!`, so let's get started. -// All formating is handled by [`std::fmt`](http://doc.rust-lang.org/std/fmt/index.html). I won't explain +// All formating is handled by [`std::fmt`](https://doc.rust-lang.org/std/fmt/index.html). I won't explain // all the details, and refer you to the documentation instead. use std::fmt; @@ -147,4 +147,4 @@ fn test_vec_min() { // of course, need a `Display` bound on `T`.) Then you should be able to use them with `println!` just like you do // with numbers, and get rid of the inherent functions to print `SomethingOrNothing` and `SomethingOrNothing`. -//@ [index](main.html) | [previous](part06.html) | [next](part08.html) +//@ [index](main.html) | [previous](part06.html) | [raw source](https://www.ralfj.de/git/rust-101.git/blob_plain/HEAD:/workspace/src/part07.rs) | [next](part08.html)