[mike@mwxm4]

goca.go

@@ -140,6 +140,12 @@ func printHelp() {
 	fmt.Println("  base <C>   Change base currency (e.g., base USD)")
 	fmt.Println("  clear      Clear the terminal screen")
 	fmt.Println("  exit/quit  Exit goca")
+	fmt.Println("\033[1mUpdates:\033[0m")
+	fmt.Println("  goca --version        Print the version")
+	fmt.Println("  goca --check-update   Look for a newer release")
+	fmt.Println("  goca --update         Download and install the newest release")
+	fmt.Println("  goca looks for a new release once a day, in the background, and says so on")
+	fmt.Println("  stderr. GOCA_NO_UPDATE_CHECK=1 or -y turns that off.")
 }
 
 type CalcCompleter struct{}
@@ -533,22 +539,55 @@ func handleLine(line string, useReadline bool, variablesFile string, functionsFi
 	return false
 }
 
-func main() {
-	initUnits()
+// printUpdateHint puts the note of the daily look on stderr, dimmed, so that it
+// never lands in a pipe that only expects the result.
+func printUpdateHint(hint string) {
+	if hint != "" {
+		fmt.Fprintf(os.Stderr, "\033[2m%s\033[0m\n", hint)
+	}
+}
 
+func main() {
+	// The options come before everything else: --update-refresh is the
+	// background run and must touch neither units nor rates, and --version has
+	// to answer at once — the updater probes the downloaded binary with it.
 	optY := false
 	newArgs := []string{os.Args[0]}
 	for i := 1; i < len(os.Args); i++ {
-		if os.Args[i] == "-y" {
+		switch os.Args[i] {
+		case "-y":
 			optY = true
-		} else {
+		case "--version":
+			fmt.Printf("goca %s\n", Version)
+			return
+		case "--update":
+			if err := selfUpdate.install(os.Stdout); err != nil {
+				fmt.Fprintf(os.Stderr, "goca: %v\n", err)
+				os.Exit(1)
+			}
+			return
+		case "--check-update":
+			if err := selfUpdate.check(os.Stdout); err != nil {
+				fmt.Fprintf(os.Stderr, "goca: %v\n", err)
+				os.Exit(1)
+			}
+			return
+		case updateRefreshFlag: // the background run, not in the help
+			selfUpdate.refresh()
+			return
+		default:
 			newArgs = append(newArgs, os.Args[i])
 		}
 	}
 	os.Args = newArgs
 
+	initUnits()
+
+	// Costs nothing: the hint comes from the note in the cache, and the asking
+	// happens once a day at most, in the background. -y keeps it quiet.
+	updateHint := ""
 	if !optY {
-		checkforupdate(UPDATEURL)
+		updateHint = selfUpdate.daily()
 	}
 
 	hasArgs := len(os.Args) > 1
@@ -576,6 +615,7 @@ func main() {
 			if arg == "-p" || arg == "--port" {
 				if i+1 < len(os.Args) {
 					port := os.Args[i+1]
+					printUpdateHint(updateHint)
 					startWebServer(port)
 					return
 				} else {
@@ -587,6 +627,7 @@ func main() {
 
 		input := strings.Join(os.Args[1:], " ")
 		handleLine(input, false, variablesFile, functionsFile)
+		printUpdateHint(updateHint)
 		return
 	}
 
@@ -614,6 +655,7 @@ func main() {
 
 	if useReadline {
 		fmt.Printf("\033[1;34mgoca v%s\033[0m, type 'help' for examples.\n", Version)
+		printUpdateHint(updateHint)
 	}
 
 	var scanner *bufio.Scanner
@@ -639,4 +681,8 @@ func main() {
 			break
 		}
 	}
+
+	if !useReadline { // piped input: the hint comes at the end, not before it
+		printUpdateHint(updateHint)
+	}
 }