Recover - a poor man's catch ;)

16_panic.go

@@ -3,6 +3,7 @@ package main
 import (
  "fmt"
  "net/http"
+ "log"
 )
 
 func pan1(){
@@ -15,14 +16,31 @@ func pan1(){
 func pan2(){
  // Custom panic
  fmt.Println("start")
+ // panic happens after defered statements
+ defer fmt.Println("this was deferred")
+ panic("something bad happened")
+ fmt.Println("end")
+}
+
+func pan3(){
+ // Custom panic
+ fmt.Println("start")
+ // Defering an anonymous function call - a call, so there are parentheses at the end
+ defer func(){
+ // recover returns nil if everything is ok (app is not panicing)
+ // else it's returning the actual error
+ if err := recover(); err != nil {
+ log.Println("Error:", err)
+ }
+ }()
  panic("something bad happened")
  fmt.Println("end")
 }
 
 // Custom web app
 // returns Hello Go, on https://localhost:8080/
 // panics when port is blocked, so trying to run a second copy of the app will panic
-func pan3(){
+func pan4(){
  http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request){
  w.Write([]byte("Hello Go!"))
  })
@@ -36,4 +54,5 @@ func main(){
  //pan1()
  //pan2()
  pan3()
+ //pan4()
 }

17_recover.go

@@ -0,0 +1,28 @@
+package main
+
+import(
+ "fmt"
+ "log"
+)
+
+func main(){
+ fmt.Println("start")
+ panicker()
+ fmt.Println("end")
+}
+
+func panicker(){
+ fmt.Println("about to panic")
+ defer func(){
+ if err := recover(); err != nil {
+ log.Println("Error:", err)
+ // if the error is serious we can re-panic
+ // in that case the main function will panic as well
+ // without the panic, only this internal function will stop executing
+ // main will live on and print the "end" text
+ //panic(err)
+ }
+ }()
+ panic("something bad happened")
+ fmt.Println("done panicking")
+}