finished ch10

.obsidian/workspace.json

@@ -13,12 +13,26 @@
             "state": {
               "type": "markdown",
               "state": {
-                "file": "Lifetimes.md",
+                "file": "Generic Types Traits and Lifetimes.md",
                 "mode": "source",
                 "source": false
               },
               "icon": "lucide-file",
-              "title": "Lifetimes"
+              "title": "Generic Types Traits and Lifetimes"
+            }
+          },
+          {
+            "id": "53b36d00b704136e",
+            "type": "leaf",
+            "state": {
+              "type": "markdown",
+              "state": {
+                "file": "Traits.md",
+                "mode": "source",
+                "source": false
+              },
+              "icon": "lucide-file",
+              "title": "Traits"
             }
           }
         ]
@@ -166,9 +180,11 @@
   },
   "active": "caf0233e624d6c1c",
   "lastOpenFiles": [
-    "2025-02-04.md",
-    "Lifetimes.md",
+    "Traits.md",
+    "Generics.md",
     "Generic Types Traits and Lifetimes.md",
+    "Lifetimes.md",
+    "2025-02-04.md",
     "data_types.md",
     "Collection of Common Data Structs.md",
     "Constants.md",
@@ -176,7 +192,6 @@
     "Data Types.md",
     "Enums.md",
     "Error Handling.md",
-    "Generics.md",
     "Hash.md",
     "Modules and Use.md",
     "ownership.md",
@@ -188,7 +203,6 @@
     "Reducing_Code_Duplication.md",
     "String.md",
     "Structures.md",
-    "Traits.md",
     "Variables.md",
     "Vector.md",
     "Reducing.md",

Generic Types Traits and Lifetimes.md

@@ -18,4 +18,33 @@ This chapter covers 3 things
 1. [Reducing Code duplication](Reducing_Code_Duplication.md)
 1. [Generics](Generics.md)
 1. [Traits](Traits.md)
-1. [Lifetimes](Lifetimes.md)
+2. [Lifetimes](Lifetimes.md)
+
+## Generic Type Parameters, Trait Bounds, and Lifetimes Together
+Here is an example with all of them together
+```rust
+use std::fmt::Display;
+
+fn longest_with_an_announcement<'a, T>(
+    x: &'a str,
+    y: &'a str,
+    ann: T,
+) -> &'a str
+where
+    T: Display,
+{
+    println!("Announcement! {ann}");
+    if x.len() > y.len() {
+        x
+    } else {
+        y
+    }
+}
+```
+This is the `longest` function that returns the longer of the two string slices.
+
+Now it has a parameter called `ann` of the generic type `T` which can only be any type that implements the `Display` trait as specified by the `where` clause
+
+The `ann` parameter will be printed using `{}`, which is why the `Display` trait is necessary
+
+Because lifetimes are a type of generic the declarations of the lifetime parameter `'a` and the generic type parameter `T` go in the same list inside the angle brackets after the function name

Lifetimes.md

@@ -442,3 +442,21 @@ There are two input lifetimes, so Rust applies the first lifetime elision rule a
 Then because, because one of the parameters is `&self` the return type gets the lifetime of `&self` and all lifetimes have been dealt with
 
 ## The Static Lifetime
+One special lifetime is the `'static`, which denotes that the affected reference *can* live for the entire duration of the program
+
+All string literals have the `'static` lifetime always
+
+Here is how we can annotate it
+```rust
+let s: &'static str = "I have a static lifetime.";
+```
+
+The string literal is stored in the program's binary which is always available
+
+You might see suggestions to use `'static` lifetime in the error message.
+
+Think about whether or not the value being referenced/the reference will always be valid before adding it
+
+Most of the time the suggestion comes from attempting to create a dangling reference or a mismatch of the available lifetimes, instead of adding a `'static` lifetime annotation
+
+Instead the solution is to fix those problems

Traits.md

@@ -2,11 +2,11 @@
 
 This is used to defined shared behavior
 
-A *trait* defines the fnctionality a particular type has and can share with other tpyes.
+A *trait* defines the functionality a particular type has and can share with other types.
 
-Traits are ued to define shared behavior in an abstract way.
+Traits are used to define shared behavior in an abstract way.
 
-We can use *trait bounds* to specifty that a generic type can be any type that has certain behavior
+We can use *trait bounds* to specify that a generic type can be any type that has certain behavior
 
 Note: Traits are similar to a feature often called *interfaces* in other languages, but there are some differences in Rust
 
@@ -16,15 +16,15 @@ A type's behavior consists of the methods we can call on that type
 
 Some types can share the same behavior if we can call the same methods on all of those types.
 
-Trait definitions are a way to gropu method singatures together to define a set of behaviors necessary to accomplish something.
+Trait definitions are a way to group method signatures together to define a set of behaviors necessary to accomplish something.
 
-Here is an exmaple to lay this out
+Here is an example to lay this out
 
 lets say you have multiple structs that hold various kinds and amounts of text
-`NewsArticle` struct that holds a news story filed in a particular locaion
+`NewsArticle` struct that holds a news story filed in a particular location
 `Tweet` that can have, at most, 280 characters along with metadata that indicates whether it was a new tweet, a retweet, or a reply to another tweet
 
-We want to make a meida aggregator library crate named `aggregator` that can display summaries of data that could be stored in a `NewsArticle` or `Tweet`
+We want to make a media aggregator library crate named `aggregator` that can display summaries of data that could be stored in a `NewsArticle` or `Tweet`
 
 In order to do this we need a summary from each type, this would be done by calling a `summarize` method on an instance