finished structs ch

data_types.md

@@ -168,6 +168,7 @@ must be explicity typed to true or false
     let n = false;
     let o = true;
 ```
+&& is and operator
 
 ### Char
 must use single quotes and not "" otherwise will be inferred as string literal
@@ -550,6 +551,11 @@ impl Rectangle {
     fn area (&self) -> u32 {
         self.length * self.width
     }
+
+    // this is an example of a mthod with exterior params requried
+    fn fit_into (&self, other: &Rectangle) {
+        self.length > other.length && self.width > other.width
+    }
 }
 ```
 
@@ -572,4 +578,35 @@ just differenitate with the use of () this is for a mthod not the field
 
 this is used in getters where you want read only access to a struct, you can make the field pravate but the method public
 
-130
+## Associated Functions
+
+functions in the impl block are associated with the struct
+all functions within tthe impl block is associated functions
+
+not all associated methods have a self reference and therefore arent methods
+
+can be used in constructors or destructors, often constructors are what they are used for
+
+new is often used for constructors, not a protected keyword
+
+example
+```rust
+impl Rectangle {
+    // Self is only allowed within the impl scope, referes to what the scope is for, this determines the return type
+    fn square(side: i32) -> Self {
+        Self {
+            length = side,
+            width = side,
+        }
+    }
+}
+```
+to call these types of functions use the :: operator, this is also used in namespaces
+
+ex
+```rust
+    let square1 = Rectangle::square(3);
+```
+
+you have have multiple impl blocks associated with a struct, is the same as hvaing one monolithic one (better for readibility)
+some use cases for multiple impl blocks