Allow more than one controller to attach OnFocus/OnFocusLost functions

Trying to do this would previously have the second one silently overwrite the
first one's.

We don't currently have this in lazygit, but I ran into the situation once
during development, and it can lead to bugs that are hard to diagnose.

Instead of holding a list of functions, we could also have added a panic in case
the function was set already; this would have been good enough for the current
state, and enough to catch mistakes early in the future. However, I decided to
allow multiple controllers to attach these functions, because I can't see a
reason not to.

pkg/gui/context/base_context.go

@@ -18,8 +18,8 @@ type BaseContext struct {
 	onClickFn                func() error
 	onClickFocusedMainViewFn onClickFocusedMainViewFn
 	onRenderToMainFn         func()
-	onFocusFn                onFocusFn
-	onFocusLostFn            onFocusLostFn
+	onFocusFns               []onFocusFn
+	onFocusLostFns           []onFocusLostFn
 
 	focusable                   bool
 	transient                   bool
@@ -135,9 +135,11 @@ func (self *BaseContext) AddMouseKeybindingsFn(fn types.MouseKeybindingsFn) {
 	self.mouseKeybindingsFns = append(self.mouseKeybindingsFns, fn)
 }
 
-func (self *BaseContext) ClearAllBindingsFn() {
+func (self *BaseContext) ClearAllAttachedControllerFunctions() {
 	self.keybindingsFns = nil
 	self.mouseKeybindingsFns = nil
+	self.onFocusFns = nil
+	self.onFocusLostFns = nil
 }
 
 func (self *BaseContext) AddOnClickFn(fn func() error) {
@@ -168,13 +170,13 @@ func (self *BaseContext) AddOnRenderToMainFn(fn func()) {
 
 func (self *BaseContext) AddOnFocusFn(fn onFocusFn) {
 	if fn != nil {
-		self.onFocusFn = fn
+		self.onFocusFns = append(self.onFocusFns, fn)
 	}
 }
 
 func (self *BaseContext) AddOnFocusLostFn(fn onFocusLostFn) {
 	if fn != nil {
-		self.onFocusLostFn = fn
+		self.onFocusLostFns = append(self.onFocusLostFns, fn)
 	}
 }
 

pkg/gui/context/simple_context.go

@@ -37,8 +37,8 @@ func (self *SimpleContext) HandleFocus(opts types.OnFocusOpts) {
 		self.GetViewTrait().SetHighlight(true)
 	}
 
-	if self.onFocusFn != nil {
-		self.onFocusFn(opts)
+	for _, fn := range self.onFocusFns {
+		fn(opts)
 	}
 
 	if self.onRenderToMainFn != nil {
@@ -49,8 +49,8 @@ func (self *SimpleContext) HandleFocus(opts types.OnFocusOpts) {
 func (self *SimpleContext) HandleFocusLost(opts types.OnFocusLostOpts) {
 	self.GetViewTrait().SetHighlight(false)
 	self.view.SetOriginX(0)
-	if self.onFocusLostFn != nil {
-		self.onFocusLostFn(opts)
+	for _, fn := range self.onFocusLostFns {
+		fn(opts)
 	}
 }
 

pkg/gui/controllers.go

@@ -21,7 +21,7 @@ func (gui *Gui) Helpers() *helpers.Helpers {
 // the lower in the list the keybindings will appear.
 func (gui *Gui) resetHelpersAndControllers() {
 	for _, context := range gui.Contexts().Flatten() {
-		context.ClearAllBindingsFn()
+		context.ClearAllAttachedControllerFunctions()
 	}
 
 	helperCommon := gui.c

pkg/gui/types/context.go

@@ -88,7 +88,7 @@ type IBaseContext interface {
 
 	AddKeybindingsFn(KeybindingsFn)
 	AddMouseKeybindingsFn(MouseKeybindingsFn)
-	ClearAllBindingsFn()
+	ClearAllAttachedControllerFunctions()
 
 	// This is a bit of a hack at the moment: we currently only set an onclick function so that
 	// our list controller can come along and wrap it in a list-specific click handler.