From 26fc4b0e6268e58d7694ccf87e57de59d3b6b9a1 Mon Sep 17 00:00:00 2001
From: jpbruyere <jp.bruyere@hotmail.com>
Date: Sun, 1 Jan 2017 19:59:28 +0100
Subject: [PATCH] debug when vc of ds newVal is null

---
 Tests/BasicTests.cs                                   |  2 ++
 Tests/Interfaces/TemplatedContainer/test_Listbox.crow |  4 ++--
 src/CompilerServices/CompilerServices.cs              | 10 ++++++++++
 src/GraphicObjects/TemplatedGroup.cs                  |  2 +-
 4 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/Tests/BasicTests.cs b/Tests/BasicTests.cs
index 1ae9094f..0533729d 100644
--- a/Tests/BasicTests.cs
+++ b/Tests/BasicTests.cs
@@ -129,6 +129,8 @@ namespace Tests
 			//testFiles = new string [] { @"Interfaces/Unsorted/testFileDialog.crow" };
 			//testFiles = new string [] { @"Interfaces/Divers/colorPicker.crow" };
 			testFiles = new string [] { @"Interfaces/Divers/welcome.crow" };
+			//testFiles = new string [] { @"Interfaces/TemplatedContainer/test_Listbox.crow" };
+			//testFiles = new string [] { @"Interfaces/TemplatedControl/testItemTemplateTag.crow" };
 			//testFiles = new string [] { @"Interfaces/Divers/test2WayBinding.crow" };
 			//testFiles = new string [] { @"Interfaces/Divers/testPropLess.crow" };
 			testFiles = testFiles.Concat (Directory.GetFiles (@"Interfaces/GraphicObject", "*.crow")).ToArray ();
diff --git a/Tests/Interfaces/TemplatedContainer/test_Listbox.crow b/Tests/Interfaces/TemplatedContainer/test_Listbox.crow
index e24b399d..47adb8ce 100755
--- a/Tests/Interfaces/TemplatedContainer/test_Listbox.crow
+++ b/Tests/Interfaces/TemplatedContainer/test_Listbox.crow
@@ -5,9 +5,9 @@
 		<Label Text="{../ColorList.SelectedItem}" Background="DarkGreen"/>
 		<Label Text="{Hover}" Background="DarkGreen"/>
 		<Button Caption="Clear" Width="Stretched" MouseClick="OnClear"/>
-<!--		<ListBox Name="ColorList" Data="{TestList}"  Width="200" Height="200" 
+		<ListBox Name="ColorList" Data="{TestList}"  Width="200" Height="200" 
 					 ItemTemplate="#Tests.Interfaces.colorItem.crow">			
 		</ListBox>
-		<Button Caption="Load list" Width="Stretched" MouseClick="OnLoadList"/>-->
+		<Button Caption="Load list" Width="Stretched" MouseClick="OnLoadList"/>
 	</VerticalStack>
 </Border>
\ No newline at end of file
diff --git a/src/CompilerServices/CompilerServices.cs b/src/CompilerServices/CompilerServices.cs
index c0acc5d5..42ae5f7b 100644
--- a/src/CompilerServices/CompilerServices.cs
+++ b/src/CompilerServices/CompilerServices.cs
@@ -456,7 +456,14 @@ namespace Crow
 			il.MarkLabel (convert);
 
 			if (dstType == typeof(string)) {
+				System.Reflection.Emit.Label emitNullStr = il.DefineLabel ();
+				il.Emit (OpCodes.Dup);
+				il.Emit (OpCodes.Brfalse, emitNullStr);
 				il.Emit (OpCodes.Callvirt, CompilerServices.miObjToString);
+				il.Emit (OpCodes.Br, endConvert);
+				il.MarkLabel (emitNullStr);
+				il.Emit (OpCodes.Pop);//remove null string from stack
+				il.Emit (OpCodes.Ldstr, "");//replace with empty string
 			} else if (dstType.IsPrimitive) {
 				//il.Emit (OpCodes.Unbox_Any, dstType);
 				il.Emit (OpCodes.Callvirt, CompilerServices.GetConvertMethod (dstType));
@@ -464,7 +471,10 @@ namespace Crow
 				il.Emit (OpCodes.Unbox_Any, dstType);
 			} else{
 				il.Emit (OpCodes.Stloc_0); //save orig value in loc0
+				//first check if not null
 				il.Emit (OpCodes.Ldloc_0);
+				il.Emit (OpCodes.Dup);
+				il.Emit (OpCodes.Brfalse, endConvert);
 				il.Emit (OpCodes.Callvirt, miGetType);
 				il.Emit (OpCodes.Ldtoken, dstType);//push destination property type for testing
 				il.Emit (OpCodes.Call, CompilerServices.miGetTypeFromHandle);
diff --git a/src/GraphicObjects/TemplatedGroup.cs b/src/GraphicObjects/TemplatedGroup.cs
index 3c1fed9e..b05aad9f 100644
--- a/src/GraphicObjects/TemplatedGroup.cs
+++ b/src/GraphicObjects/TemplatedGroup.cs
@@ -135,7 +135,7 @@ namespace Crow
 
 				NotifyValueChanged ("Data", data);
 
-				//lock (CurrentInterface.UpdateMutex)
+				lock (CurrentInterface.UpdateMutex)
 					ClearItems ();
 
 				if (data == null)
-- 
2.47.3