[Author: thakis]

Make implicit assumptions in GTMWindowSheetController explicit by
adding asserts.

Original review at http://codereview.appspot.com/4418041/

R=avi
APPROVED=avi
DELTA=8  (6 added, 0 deleted, 2 changed)

2 files changed, 8 insertions, 2 deletions

diff --git a/AppKit/GTMWindowSheetController.h b/AppKit/GTMWindowSheetController.h
index 558814e..7991112 100644
--- a/AppKit/GTMWindowSheetController.h
+++ b/AppKit/GTMWindowSheetController.h
@@ -74,8 +74,11 @@
             delegate:(id <GTMWindowSheetControllerDelegate>)delegate;
 
 // Starts a view modal session for a sheet. Intentionally similar to
-// -[NSApplication beginSheet:modalForWindow:modalDelegate:didEndSelector:
-//                contextInfo:].
+// -[NSApplication
+//    beginSheet:modalForWindow:modalDelegate:didEndSelector:contextInfo:].
+// You must only call this method if the currently active view is |view| or
+// |nil|; this means you can call this method only after creating the
+// GTMWindowSheetController or after calling -setActiveView:view.
 //
 // Args:
 //            sheet: The window object representing the sheet you want to
diff --git a/AppKit/GTMWindowSheetController.m b/AppKit/GTMWindowSheetController.m
index bf85e59..92e2526 100644
--- a/AppKit/GTMWindowSheetController.m
+++ b/AppKit/GTMWindowSheetController.m
@@ -339,6 +339,9 @@ willPositionSheet:(NSWindow*)sheet
   }
   [invocation invokeWithTarget:systemSheet];
 
+  _GTMDevAssert(!activeView_ || activeView_ == view,
+                @"You have to call setActiveView:view before "
+                 "calling beginSheet:modalForView:view");
   activeView_ = view;
 }