Add Application.HandlePanic

Resolves #74.

CHANGELOG

@@ -1,4 +1,5 @@
 v1.5.7 (WIP)
+- Add Application.HandlePanic
 - Add Modal.SetButtonsAlign and Modal.SetTextAlign
 - Fix TextView.GetRegionText error when text contains color tags
 - Fix TextView region tags when placed at the end of a line

application.go

@@ -125,6 +125,23 @@ func NewApplication() *Application {
 	}
 }
 
+// HandlePanic (when deferred at the start of a goroutine) handles panics
+// gracefully. The terminal is returned to its original state before the panic
+// message is printed.
+//
+// Panics may only be handled by the panicking goroutine. Because of this,
+// HandlePanic must be deferred at the start of each goroutine (including main).
+func (a *Application) HandlePanic() {
+	p := recover()
+	if p == nil {
+		return
+	}
+
+	a.finalizeScreen()
+
+	panic(p)
+}
+
 // SetInputCapture sets a function which captures all key events before they are
 // forwarded to the key event handler of the primitive which currently has
 // focus. This function can then choose to forward that key event (or a
@@ -290,15 +307,7 @@ func (a *Application) Run() error {
 		return err
 	}
 
-	// We catch panics to clean up because they mess up the terminal.
-	defer func() {
-		if p := recover(); p != nil {
-			if a.screen != nil {
-				a.screen.Fini()
-			}
-			panic(p)
-		}
-	}()
+	defer a.HandlePanic()
 
 	// Draw the screen for the first time.
 	a.Unlock()
@@ -308,6 +317,8 @@ func (a *Application) Run() error {
 	var wg sync.WaitGroup
 	wg.Add(1)
 	go func() {
+		defer a.HandlePanic()
+
 		defer wg.Done()
 		for {
 			a.RLock()
@@ -431,6 +442,8 @@ func (a *Application) Run() error {
 	semaphore := &sync.Mutex{}
 
 	go func() {
+		defer a.HandlePanic()
+
 		for update := range a.updates {
 			semaphore.Lock()
 			update()
@@ -570,13 +583,18 @@ func (a *Application) Stop() {
 	a.Lock()
 	defer a.Unlock()
 
+	a.finalizeScreen()
+	a.screenReplacement <- nil
+}
+
+func (a *Application) finalizeScreen() {
 	screen := a.screen
 	if screen == nil {
 		return
 	}
+
 	a.screen = nil
 	screen.Fini()
-	a.screenReplacement <- nil
 }
 
 // Suspend temporarily suspends the application by exiting terminal UI mode and

demos/box/main.go

@@ -8,6 +8,7 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
 
 	box := cview.NewBox()
 	box.SetBorder(true)

demos/button/main.go

@@ -5,6 +5,8 @@ import "code.rocketnine.space/tslocum/cview"
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	button := cview.NewButton("Hit Enter to close")

demos/checkbox/main.go

@@ -7,6 +7,8 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	checkbox := cview.NewCheckBox()

demos/dropdown/main.go

@@ -5,6 +5,8 @@ import "code.rocketnine.space/tslocum/cview"
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	dropdown := cview.NewDropDown()

demos/flex/main.go

@@ -14,6 +14,8 @@ func demoBox(title string) *cview.Box {
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	subFlex := cview.NewFlex()

demos/focusmanager/main.go

@@ -18,6 +18,8 @@ func wrap(f func()) func(ev *tcell.EventKey) *tcell.EventKey {
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	input1 := cview.NewInputField()

demos/form/main.go

@@ -7,6 +7,8 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	form := cview.NewForm()

demos/frame/main.go

@@ -8,6 +8,8 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	box := cview.NewBox()

demos/grid/main.go

@@ -7,6 +7,8 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	newPrimitive := func(text string) cview.Primitive {

demos/inputfield/autocomplete/main.go

@@ -12,6 +12,7 @@ const wordList = "ability,able,about,above,accept,according,account,across,act,a
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
 
 	words := strings.Split(wordList, ",")
 

demos/inputfield/autocompleteasync/main.go

@@ -17,6 +17,8 @@ type company struct {
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	inputField := cview.NewInputField()
 	inputField.SetLabel("Enter a company name: ")
 	inputField.SetFieldWidth(30)

demos/inputfield/simple/main.go

@@ -8,6 +8,8 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	inputField := cview.NewInputField()

demos/list/main.go

@@ -9,6 +9,8 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	list := cview.NewList()

demos/modal/main.go

@@ -7,6 +7,8 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	modal := cview.NewModal()

demos/panels/main.go

@@ -11,6 +11,8 @@ const panelCount = 5
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	panels := cview.NewPanels()

demos/presentation/main.go

@@ -43,6 +43,8 @@ var app = cview.NewApplication()
 
 // Starting point for the presentation.
 func main() {
+	defer app.HandlePanic()
+
 	var debugPort int
 	flag.IntVar(&debugPort, "debug", 0, "port to serve debug info")
 	flag.Parse()

demos/primitive/main.go

@@ -61,6 +61,7 @@ func (r *RadioButtons) InputHandler() func(event *tcell.EventKey, setFocus func(
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
 
 	radioButtons := NewRadioButtons([]string{"Lions", "Elephants", "Giraffes"})
 	radioButtons.SetBorder(true)

demos/progressbar/main.go

@@ -9,6 +9,7 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
 
 	grid := cview.NewGrid()
 	grid.SetColumns(-1, 6, 4, 30, -1)

demos/tabbedpanels/main.go

@@ -11,6 +11,8 @@ const panelCount = 5
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	panels := cview.NewTabbedPanels()

demos/table/main.go

@@ -12,6 +12,8 @@ const loremIpsumText = "Lorem ipsum dolor sit amet, consetetur sadipscing elitr,
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	table := cview.NewTable()

demos/textview/main.go

@@ -21,6 +21,8 @@ Capitalize on low hanging fruit to identify a ballpark value added activity to b
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	textView := cview.NewTextView()

demos/treeview/main.go

@@ -12,6 +12,8 @@ import (
 // Show a navigable tree view of the current directory.
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	app.EnableMouse(true)
 
 	rootDir := "."

demos/unicode/main.go

@@ -9,6 +9,8 @@ import (
 
 func main() {
 	app := cview.NewApplication()
+	defer app.HandlePanic()
+
 	panels := cview.NewPanels()
 
 	form := cview.NewForm()

doc_test.go

@@ -10,6 +10,8 @@ import (
 func ExampleNewApplication() {
 	// Initialize application.
 	app := NewApplication()
+	// Handle panics gracefully.
+	defer app.HandlePanic()
 
 	// Create shared TextView.
 	sharedTextView := NewTextView()
@@ -71,6 +73,8 @@ func ExampleNewApplication() {
 func ExampleApplication_EnableMouse() {
 	// Initialize application.
 	app := NewApplication()
+	// Handle panics gracefully.
+	defer app.HandlePanic()
 
 	// Enable mouse support.
 	app.EnableMouse(true)