CLSCompliantAttribute

Syntax#

[assembly:CLSCompliant(true)]
[CLSCompliant(true)]

Parameters#

Constructor	Parameter
CLSCompliantAttribute(Boolean)	Initializes an instance of the CLSCompliantAttribute class with a Boolean value indicating whether the indicated program element is CLS-compliant.
## Remarks#
The Common Language Specification (CLS) is a set of base rules to which any language targeting the CLI(language which confirms the Common Language Infrastructure specifications) should confirm in order to interoperate with other CLS-compliant languages.

List of CLI languages

You should mark your assembly as CLSCompliant in most cases when you are distributing libraries. This attribute will guarantee you that your code will be usable by all CLS-compliant languages. This means that your code can be consumed by any language that can be compiled and run on CLR(Common Language Runtime)

When your assembly is marked with CLSCompliantAttribute, the compiler will check if your code violates any of CLS rules and return warning if it is needed.

Access Modifier to which CLS rules apply

using System;

[assembly:CLSCompliant(true)]
namespace CLSDoc
{
   
    public class Cat
    {
        internal UInt16 _age = 0;
        private UInt16 _daysTillVacination = 0;

        //Warning CS3003  Type of 'Cat.DaysTillVacination' is not CLS-compliant
        protected UInt16 DaysTillVacination
        {
            get { return _daysTillVacination; }
        }

        //Warning    CS3003    Type of 'Cat.Age' is not CLS-compliant
        public UInt16 Age
        { get { return _age; } }

        //valid behaviour by CLS-compliant rules
        public int IncreaseAge()
        {
            int increasedAge = (int)_age + 1;
           
            return increasedAge;
        }

    }
}

The rules for CLS compliance apply only to a public/protected components.

Violation of CLS rule: Unsigned types / sbyte

using System;

[assembly:CLSCompliant(true)]
namespace CLSDoc
{
   
    public class Car
    {
        internal UInt16 _yearOfCreation = 0;

        //Warning CS3008  Identifier '_numberOfDoors' is not CLS-compliant 
        //Warning CS3003  Type of 'Car._numberOfDoors' is not CLS-compliant 
        public UInt32 _numberOfDoors = 0;

        //Warning    CS3003    Type of 'Car.YearOfCreation' is not CLS-compliant
        public UInt16 YearOfCreation
        {
            get { return _yearOfCreation; }
        }


        //Warning CS3002  Return type of 'Car.CalculateDistance()' is not CLS-compliant
        public UInt64 CalculateDistance()
        {
            return 0;
        }

        
        //Warning CS3002  Return type of 'Car.TestDummyUnsignedPointerMethod()' is not CLS-compliant 
        public UIntPtr TestDummyUnsignedPointerMethod()
        {
            int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
            UIntPtr ptr = (UIntPtr)arr[0];

            
            return ptr;
        }

        //Warning CS3003  Type of 'Car.age' is not CLS-compliant 
        public sbyte age = 120;


    }
}

Violation of CLS rule: Same naming

using System;

[assembly:CLSCompliant(true)]
namespace CLSDoc
{
   
    public class Car
    {
        //Warning    CS3005    Identifier 'Car.CALCULATEAge()' differing only in case is not CLS-compliant
        public int CalculateAge()
        {
            return 0;
        }

        public int CALCULATEAge()
        {
            return 0;
        }

    }
}

Visual Basic is not case sensitive

Violation of CLS rule: Identifier _

using System;

[assembly:CLSCompliant(true)]
namespace CLSDoc
{
   
    public class Car
    {
        //Warning CS3008  Identifier '_age' is not CLS-complian    
        public int _age = 0;    
    }

}

You can not start variable with _

Violation of CLS rule: Inherit from non CLSComplaint class

using System;

[assembly:CLSCompliant(true)]
namespace CLSDoc
{

    [CLSCompliant(false)]
    public class Animal
    {
        public int age = 0;
    }
  
    //Warning    CS3009    'Dog': base type 'Animal' is not CLS-compliant
    public class Dog : Animal
    {
    }

}