Why is this name with an underscore not CLS Compliant?

Question

Why do I get the compiler warning

Identifier \'Logic.DomainObjectBase._isNew\' is not CLS-compliant

for the following code?

Answer 1

CLS compliance has to do with interoperability between the different .NET languages. The property is not CLS compliant, because it starts with an underscore and is public (note: protected properties in a public class can be accessed from outside the assembly). Although this will work if the property is accessed from C# it may not if it is accessed from other .NET languages that don't allow underscores at the start of property names, hence it is not CLS-compliant.

You are getting this compiler error, because somewhere in your code you have labelled your assembly as CLS compliant with a line something like this:

[assembly: CLSCompliant(true)]

Visual Studio includes this line in the AssemblyInfo.cs file which can be found under Properties in most projects.

To get around this error you can either:

1. Rename your property (recommended):

   protected bool isNew;
   

2. Set your whole assembly to be non CLS compliant:

   [assembly: CLSCompliant(false)]
   

3. Add an attribute just to your property:

   [CLSCompliant(false)]  
   protected bool _isNew;
   

4. Change the scope of the property, so that it can not be seen outside the assembly.

   private bool _isNew;