YapDatabaseExtension.m in motion-yapper-0.0.2

- old
+ new

@@ -8,14 +8,39 @@
                     withTransaction:(YapDatabaseReadWriteTransaction *)transaction
 {
 	NSAssert(NO, @"Missing required method(%@) in class(%@)", NSStringFromSelector(_cmd), [self class]);
 }
 
+/**
+ * Subclasses may OPTIONALLY implement this method.
+ *
+ * If an extension class is renamed this method should be used to properly transition.
+ * The extension architecture will verify that a re-registered extension is using the same
+ * extension class that it was previously using. If the class names differ, then the extension architecture
+ * will automatically try to unregister the previous extension using the previous extension class.
+ *
+ * That is, it will attempt to invoke [PreviousExtensionClass dropTablesForRegisteredName: withTransaction:].
+ * Of course this won't work because the PreviousExtensionClass no longer exists.
+ * So the end result is that you will likely see the database spit out a warning like this:
+ *
+ * - Dropping tables for previously registered extension with name(order),
+ *     class(YapDatabaseQuack) for new class(YapDatabaseDuck)
+ * - Unable to drop tables for previously registered extension with name(order),
+ *     unknown class(YapDatabaseQuack)
+ *
+ * This method helps the extension architecture to understand what's happening, and it won't spit out any warnings.
+ *
+ * The default implementation returns nil.
+**/
 + (NSArray *)previousClassNames
 {
 	return nil;
 }
 
+/**
+ * Read-only property.
+ * Automatically set by YapDatabase instance during the registration process.
+**/
 @synthesize registeredName;
 
 /**
  * Subclasses must implement this method.
  * This method is called during the view registration process to enusre the extension supports the database type.