Clarify generic types

listings/ch10-generic-types-traits-and-lifetimes/listing-10-11/src/main.rs

@@ -1,10 +1,10 @@
-struct Point<T, U> {
-    x: T,
-    y: U,
+struct Point<X1, Y1> {
+    x: X1,
+    y: Y1,
 }
 
-impl<T, U> Point<T, U> {
-    fn mixup<V, W>(self, other: Point<V, W>) -> Point<T, W> {
+impl<X1, Y1> Point<X1, Y1> {
+    fn mixup<X2, Y2>(self, other: Point<X2, Y2>) -> Point<X1, Y2> {
         Point {
             x: self.x,
             y: other.y,

src/ch10-01-syntax.md

@@ -234,12 +234,11 @@ point is from the point at coordinates (0.0, 0.0) and uses mathematical
 operations that are available only for floating point types.
 
 Generic type parameters in a struct definition aren’t always the same as those
-you use in that struct’s method signatures. For example, Listing 10-11 defines
-the method `mixup` on the `Point<T, U>` struct from Listing 10-8. The method
-takes another `Point` as a parameter, which might have different types from the
-`self` `Point` we’re calling `mixup` on. The method creates a new `Point`
-instance with the `x` value from the `self` `Point` (of type `T`) and the `y`
-value from the passed-in `Point` (of type `W`).
+you use in that struct’s method signatures. 
+Listing 10-11 uses the generic types `X1` `Y1` for the `Point` struct and 
+`X2` `Y2` for the `mixup` method signature to make the example clearer. 
+The method creates a new `Point` instance with the `x` value from the `self` 
+`Point` (of type `X1`) and the `y` value from the passed-in `Point` (of type `Y2`).
 
 <span class="filename">Filename: src/main.rs</span>
 
@@ -260,8 +259,8 @@ call will print `p3.x = 5, p3.y = c`.
 
 The purpose of this example is to demonstrate a situation in which some generic
 parameters are declared with `impl` and some are declared with the method
-definition. Here, the generic parameters `T` and `U` are declared after `impl`,
-because they go with the struct definition. The generic parameters `V` and `W`
+definition. Here, the generic parameters `X1` and `Y1` are declared after `impl`,
+because they go with the struct definition. The generic parameters `X2` and `Y2`
 are declared after `fn mixup`, because they’re only relevant to the method.
 
 ### Performance of Code Using Generics