Subscribe to items via event methods.

Add deprecation warnings when they don’t return a disposable

spec/pane-view-spec.coffee

@@ -1,6 +1,7 @@
 PaneContainerView = require '../src/pane-container-view'
 PaneView = require '../src/pane-view'
 fs = require 'fs-plus'
+{Emitter} = require 'event-kit'
 {$, View} = require 'atom'
 path = require 'path'
 temp = require 'temp'
@@ -162,6 +163,38 @@ describe "PaneView", ->
       view2.trigger 'title-changed'
       expect(activeItemTitleChangedHandler).toHaveBeenCalled()
 
+    describe 'when there is a onDidChangeTitle method', ->
+      beforeEach ->
+        TestView::changeTitle = ->
+          @emitter.emit 'did-change-title', 'title'
+        TestView::onDidChangeTitle = (callback) ->
+          @emitter.on 'did-change-title', callback
+
+        view1.emitter = new Emitter
+        view2.emitter = new Emitter
+
+        view1.id = 1
+        view2.id = 2
+
+        pane.activateItem(view2)
+        pane.activateItem(view1)
+
+      fffit "emits pane:active-item-title-changed", ->
+        activeItemTitleChangedHandler = jasmine.createSpy("activeItemTitleChangedHandler")
+        pane.on 'pane:active-item-title-changed', activeItemTitleChangedHandler
+
+        expect(pane.getActiveItem()).toBe view1
+        view2.changeTitle()
+        expect(activeItemTitleChangedHandler).not.toHaveBeenCalled()
+
+        view1.changeTitle()
+        expect(activeItemTitleChangedHandler).toHaveBeenCalled()
+        activeItemTitleChangedHandler.reset()
+
+        pane.activateItem(view2)
+        view2.changeTitle()
+        expect(activeItemTitleChangedHandler).toHaveBeenCalled()
+
   describe "when an unmodifed buffer's path is deleted", ->
     it "removes the pane item", ->
       editor = null

src/pane-view.coffee

@@ -147,6 +147,9 @@ class PaneView extends View
     @activeItem
 
   onActiveItemChanged: (item) =>
+    @activeItemDisposables.dispose() if @activeItemDisposables?
+    @activeItemDisposables = new CompositeDisposable()
+
     if @previousActiveItem?.off?
       @previousActiveItem.off 'title-changed', @activeItemTitleChanged
       @previousActiveItem.off 'modified-status-changed', @activeItemModifiedChanged
@@ -154,15 +157,29 @@ class PaneView extends View
 
     return unless item?
 
-    hasFocus = @hasFocus()
-    if item.on?
-      item.on 'title-changed', @activeItemTitleChanged
-      item.on 'modified-status-changed', @activeItemModifiedChanged
+    if item.onDidChangeTitle?
+      disposable = item.onDidChangeTitle(@activeItemTitleChanged)
+      deprecate 'Please return a Disposable object from your ::onDidChangeTitle method!' unless disposable?.dispose?
+      @activeItemDisposables.add(disposable) if disposable?.dispose?
+    else if item.on?
+      disposable = item.on('title-changed', @activeItemTitleChanged)
+      deprecate 'Please return a Disposable object from your ::on method. Your ::off method will not be called soon!' unless disposable?.dispose?
+      @activeItemDisposables.add(disposable) if disposable?.dispose?
+
+    if item.onDidChangeModified?
+      disposable = item.onDidChangeModified(@activeItemModifiedChanged)
+      deprecate 'Please return a Disposable object from your ::onDidChangeModified method!' unless disposable?.dispose?
+      @activeItemDisposables.add(disposable) if disposable?.dispose?
+    else if item.on?
+      item.on('modified-status-changed', @activeItemModifiedChanged)
+      deprecate 'Please return a Disposable object from your ::on method. Your ::off method will not be called soon!' unless disposable?.dispose?
+      @activeItemDisposables.add(disposable) if disposable?.dispose?
+
     view = @viewForItem(item)
     otherView.hide() for otherView in @itemViews.children().not(view).views()
     @itemViews.append(view) unless view.parent().is(@itemViews)
     view.show() if @attached
-    view.focus() if hasFocus
+    view.focus() if @hasFocus()
 
     @trigger 'pane:active-item-changed', [item]