exclusive reference -> unique reference

[rust-101.git] / src / part02.rs

diff --git a/src/part02.rs b/src/part02.rs
index 41bb3bc7ea6bfcd32f64fc3450b4c73f82dc7c50..44a20d43408c92b15bd4ae675b71e16ca9eae2ef 100644 (file)
--- a/src/part02.rs
+++ b/src/part02.rs
@@ -17,13 +17,13 @@ pub enum SomethingOrNothing<T>  {
 }
 // Instead of writing out all the variants, we can also just import them all at once.
 pub use self::SomethingOrNothing::*;
 }
 // Instead of writing out all the variants, we can also just import them all at once.
 pub use self::SomethingOrNothing::*;

-//@ What this does is to define an entire family of types: We can now write
+//@ What this does is define an entire family of types: We can now write

 //@ `SomethingOrNothing<i32>` to get back our `NumberOrNothing`.
 type NumberOrNothing = SomethingOrNothing<i32>;
 //@ However, we can also write `SomethingOrNothing<bool>` or even `SomethingOrNothing<SomethingOrNothing<i32>>`.
 //@ `SomethingOrNothing<i32>` to get back our `NumberOrNothing`.
 type NumberOrNothing = SomethingOrNothing<i32>;
 //@ However, we can also write `SomethingOrNothing<bool>` or even `SomethingOrNothing<SomethingOrNothing<i32>>`.

-//@ In fact, such a type is so useful that it is already present in the standard library: It's called an
-//@ *option type*, written `Option<T>`. Go check out its [documentation](http://doc.rust-lang.org/stable/std/option/index.html)!
-//@ (And don't worry, there's indeed lots of material mentioned there that we did not cover yet.)
+//@ In fact, a type like `SomethingOrNothing` is so useful that it is already present in the standard library: It's called an
+//@ *option type*, written `Option<T>`. Go check out its [documentation](https://doc.rust-lang.org/stable/std/option/index.html)!
+//@ (And don't worry, there's indeed lots of material mentioned there that we have not covered yet.)

 
 // ## Generic `impl`, Static functions
 //@ The types are so similar, that we can provide a generic function to construct a `SomethingOrNothing<T>`
 
 // ## Generic `impl`, Static functions
 //@ The types are so similar, that we can provide a generic function to construct a `SomethingOrNothing<T>`


@@ -55,18 +55,18 @@ fn call_constructor(x: i32) -> SomethingOrNothing<i32> {
 }
 
 // ## Traits
 }
 
 // ## Traits

-//@ Now that we have a generic `SomethingOrNothing`, wouldn't it be nice to also gave a generic
+//@ Now that we have a generic `SomethingOrNothing`, wouldn't it be nice to also have a generic

 //@ `vec_min`? Of course, we can't take the minimum of a vector of *any* type. It has to be a type
 //@ supporting a `min` operation. Rust calls such properties that we may demand of types *traits*.
 
 //@ So, as a first step towards a generic `vec_min`, we define a `Minimum` trait.
 //@ For now, just ignore the `Copy`, we will come back to this point later.
 //@ A `trait` is a lot like interfaces in Java: You define a bunch of functions
 //@ `vec_min`? Of course, we can't take the minimum of a vector of *any* type. It has to be a type
 //@ supporting a `min` operation. Rust calls such properties that we may demand of types *traits*.
 
 //@ So, as a first step towards a generic `vec_min`, we define a `Minimum` trait.
 //@ For now, just ignore the `Copy`, we will come back to this point later.
 //@ A `trait` is a lot like interfaces in Java: You define a bunch of functions

-//@ you want to have implemented, and their argument and return types.<br/>
-//@ The function `min` takes to arguments of the same type, but I made the
+//@ you want to have implemented, and their argument and return types. <br/>
+//@ The function `min` takes two arguments of the same type, but I made the

 //@ first argument the special `self` argument. I could, alternatively, have
 //@ made `min` a static function as follows: `fn min(a: Self, b: Self) -> Self`.
 //@ first argument the special `self` argument. I could, alternatively, have
 //@ made `min` a static function as follows: `fn min(a: Self, b: Self) -> Self`.

-//@ However, in Rust one typically prefers methods over static function wherever possible.
+//@ However, in Rust one typically prefers methods over static functions wherever possible.

 pub trait Minimum : Copy {
     fn min(self, b: Self) -> Self;
 }
 pub trait Minimum : Copy {
     fn min(self, b: Self) -> Self;
 }


@@ -79,7 +79,7 @@ pub trait Minimum : Copy {
 //@ 
 //@ There is a crucial difference to templates in C++: We actually have to declare which traits
 //@ we want the type to satisfy. If we left away the `Minimum`, Rust would have complained that
 //@ 
 //@ There is a crucial difference to templates in C++: We actually have to declare which traits
 //@ we want the type to satisfy. If we left away the `Minimum`, Rust would have complained that

-//@ we cannot call `min`. Just try it!<br/>
+//@ we cannot call `min`. Just try it! <br/>

 //@ This is in strong contrast to C++, where the compiler only checks such details when the
 //@ function is actually used.
 pub fn vec_min<T: Minimum>(v: Vec<T>) -> SomethingOrNothing<T> {
 //@ This is in strong contrast to C++, where the compiler only checks such details when the
 //@ function is actually used.
 pub fn vec_min<T: Minimum>(v: Vec<T>) -> SomethingOrNothing<T> {


@@ -98,7 +98,7 @@ pub fn vec_min<T: Minimum>(v: Vec<T>) -> SomethingOrNothing<T> {
 //@ Before going on, take a moment to ponder the flexibility of Rust's take on abstraction:
 //@ We just defined our own, custom trait (interface), and then implemented that trait
 //@ *for an existing type*. With the hierarchical approach of, e.g., C++ or Java,
 //@ Before going on, take a moment to ponder the flexibility of Rust's take on abstraction:
 //@ We just defined our own, custom trait (interface), and then implemented that trait
 //@ *for an existing type*. With the hierarchical approach of, e.g., C++ or Java,

-//@ that's not possible: We cannot make an existing type suddenly also inherit from our abstract base class.
+//@ that's not possible: We cannot make an existing type also inherit from our abstract base class after the fact.

 //@ 
 //@ In case you are worried about performance, note that Rust performs *monomorphisation*
 //@ of generic functions: When you call `vec_min` with `T` being `i32`, Rust essentially goes
 //@ 
 //@ In case you are worried about performance, note that Rust performs *monomorphisation*
 //@ of generic functions: When you call `vec_min` with `T` being `i32`, Rust essentially goes


@@ -141,9 +141,9 @@ pub fn main() {
     min.print();
 }
 
     min.print();
 }
 

-//@ If this printed `3`, then you generic `vec_min` is working! So get ready for the next part.
+//@ If this printed `3`, then your generic `vec_min` is working! So get ready for the next part.

 
 // **Exercise 02.1**: Change your program such that it computes the minimum of a `Vec<f32>` (where `f32` is the type
 // of 32-bit floating-point numbers). You should not change `vec_min` in any way, obviously!
 
 
 // **Exercise 02.1**: Change your program such that it computes the minimum of a `Vec<f32>` (where `f32` is the type
 // of 32-bit floating-point numbers). You should not change `vec_min` in any way, obviously!
 

-//@ [index](main.html) | [previous](part01.html) | [next](part03.html)
+//@ [index](main.html) | [previous](part01.html) | [raw source](https://www.ralfj.de/git/rust-101.git/blob_plain/HEAD:/workspace/src/part02.rs) | [next](part03.html)