[assembly:CLSCompliant(true)]
// Errors appear because the class is public p u b l i c c lass App {
// Error: Return type of ÔApp.Abc()’ is not CLS-c o m p l i a n t public UInt32 Abc() { return 0; }
// Error: Identifier ÔApp.abc()’ differing // only in case is not CLS-c o m p l i a n t public void
abc() { }
// No error: Method is private private UInt32 ABC() { return 0; } }
In this code, the [assembly:CLSCompliant(true)] attribute is applied to the assembly. This attribute tells the compiler to ensure that any publicly exposed type doesn’t have any construct that would prevent the type from being accessed from any other programming language. When this code is compiled, the C# compiler emits two errors. The first error is reported because the method Abc returns an unsigned integer; Visual Basic and some other languages can’t manipulate unsigned integer values. The second error is because this type exposes two public methods that differ only by case: Abc and abc. Visual Basic and some other languages can’t call both these methods. Interestingly, if you were to delete public from in front of Ôclass App’ and recompile, both errors would go away. The reason is that the App type would default to internal and would therefore no longer be exposed outside the assembly. For a complete list of CLS rules, refer to the "Cross-Language Interoperability" section in the .NET Framework SDK documentation. Let me distill the CLS rules to something very simple. In the CLR, every member of a type is either a field (data) or a method (behavior). This means that every programming language