Differences

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--- go_tour_notes [2018/04/14 08:44] – [Methods and type aliasing] rpjday
+++ go_tour_notes [2018/04/14 08:57] (current) – [Refresher: pointer-based function] rpjday
@@ Line 686: / Line 686: @@
 ===== Methods with pointer receivers =====
-==== Refresher ====
+==== Refresher: call-by-value ====
-Simple example of call-by-value function and returning the result:
+Call-by-value function, which makes a //copy// of the argument:
 <code>
@@ Line 711: / Line 711: @@
         fmt.Println(v)
         fmt.Println(Scale(v, 10))
+        fmt.Println(v)
 }
+{3 4}
+{30 40}
+{3 4}
+</code>
+==== Refresher: pointer-based function ====
+Pointer-based call:
+<code>
+package main
+import (
+        "fmt"
+)
+type Vertex struct {
+        X, Y float64
+}
+func Scale(v *Vertex, f float64) {
+        v.X = v.X * f
+        v.Y = v.Y * f
+}
+func main() {
+        v := Vertex{3, 4}
+        fmt.Println(v)
+        Scale(&v, 10)
+        fmt.Println(v)
+}
+{3 4}
+{30 40}
 </code>
+Notes about the above:
+  * Even if the arg is a pointer, Go allows you to use "." to dereference.
+  * You cannot support both variations of that function