Implementing examples for error & panic handling

Author: symonk

errors/main.go

@@ -1,5 +1,43 @@
 package errors
-
+/*
+In golang it is perfectly normal for functions & methods to return an error to indicate an exception
+which differs greatly from most languages.  By convention the error should be the last item returned.
+*/
 func Run() {
+  returningAnError(15)
+  handlingAnError()
+  recoveringIfPanics()
+}
+
+type MyNewError struct {
+  number int
+}
+
+func (m *MyNewError) Error() string {
+  return fmt.Sprintf("%d was less than 10!", m.number)
+}
+
+// An example of conditionally returning an error under some circumstance.
+func returningAnError(argument int) (int, error) {
+  if argument < 10 {
+    return argument, &MyNewError(number: argument)
+  }
+  return argument, nil
+}
+
+// How to handle an error, 'raising' if something bad happens
+func handlingAnError() {
+  value, err := returnAnError(100)
+  if err != nil {
+    panic(err)
+  }
+}
 
+// Panics can be 'caught' and handled using the `recover` builtin idiom
+func recoveringIfPanics() {
+  defer func() {
+    if r := recover(); r != nil {
+      fmt.Println("Recovered from error:\n", r)
+    }()
+  }
 }