Fixed null reference exception when loading/generating code in the python forms designer when a control's property was null.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/branches/3.0@4564 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/AddIns/BackendBindings/Python/PythonBinding/Project/Src/PythonControlFieldExpression.cs

@@ -255,6 +255,19 @@ namespace ICSharpCode.PythonBinding
 			}
 			return SetPropertyValue(component, memberName, propertyValue);
 		}
+		
+		/// <summary>
+		/// Converts the value to the property's type if required.
+		/// </summary>
+		public static object ConvertPropertyValue(PropertyDescriptor propertyDescriptor, object propertyValue)
+		{
+			if (propertyValue != null) {
+				if (!propertyDescriptor.PropertyType.IsAssignableFrom(propertyValue.GetType())) {
+					return propertyDescriptor.Converter.ConvertFrom(propertyValue);
+				}
+			}
+			return propertyValue;
+		}		
 						
 		/// <summary>
 		/// Gets the member object that matches the field member.
@@ -399,16 +412,5 @@ namespace ICSharpCode.PythonBinding
 			}
 			return false;
 		}
-
-		/// <summary>
-		/// Converts the value to the property's type if required.
-		/// </summary>
-		static object ConvertPropertyValue(PropertyDescriptor propertyDescriptor, object propertyValue)
-		{
-			if (!propertyDescriptor.PropertyType.IsAssignableFrom(propertyValue.GetType())) {
-				return propertyDescriptor.Converter.ConvertFrom(propertyValue);
-			}
-			return propertyValue;
-		}		
 	}
 }

src/AddIns/BackendBindings/Python/PythonBinding/Project/Src/PythonPropertyValueAssignment.cs

@@ -35,6 +35,10 @@ namespace ICSharpCode.PythonBinding
 		/// </remarks>
 		public static string ToString(object propertyValue)
 		{
+			if (propertyValue == null) {
+				return "None";
+			}
+			
 			Type propertyType = propertyValue.GetType();
 			if (propertyType == typeof(String)) {
 				return GetQuotedString((string)propertyValue);

src/AddIns/BackendBindings/Python/PythonBinding/Test/Designer/PythonControlFieldExpressionTests.cs

@@ -6,6 +6,7 @@
 // </file>
 
 using System;
+using System.ComponentModel;
 using System.Windows.Forms;
 using ICSharpCode.PythonBinding;
 using IronPython.Compiler.Ast;
@@ -260,6 +261,15 @@ namespace PythonBinding.Tests.Designer
 			}
 		}
 		
+		[Test]
+		public void NullPropertyValueConversion()
+		{
+			using (Form form = new Form()) {
+				PropertyDescriptor descriptor = TypeDescriptor.GetProperties(form).Find("Text", true);
+				Assert.IsNull(PythonControlFieldExpression.ConvertPropertyValue(descriptor, null));
+			}
+		}
+		
 		void AssertAreEqual(PythonControlFieldExpression field, string variableName, string memberName, string methodName, string fullMemberName)
 		{
 			string expected = "Variable: " + variableName + " Member: " + memberName + " Method: " + methodName + " FullMemberName: " + fullMemberName;

src/AddIns/BackendBindings/Python/PythonBinding/Test/Designer/PythonPropertyAssignmentToStringTests.cs

@@ -105,5 +105,11 @@ namespace PythonBinding.Tests.Designer
 		{
 			Assert.AreEqual("System.Windows.Forms.Cursors.Default", PythonPropertyValueAssignment.ToString(Cursors.Default));
 		}
+		
+		[Test]
+		public void NullConversion()
+		{
+			Assert.AreEqual("None", PythonPropertyValueAssignment.ToString(null));
+		}
 	}
 }