C# Type GenericParameterAttributes

Description

Type GenericParameterAttributes gets a combination of GenericParameterAttributes flags that describe the covariance and special constraints of the current generic type parameter.

Syntax

Type.GenericParameterAttributes has the following syntax.


public virtual GenericParameterAttributes GenericParameterAttributes { get; }

Example

The following code example defines a generic type Test with two type parameters that have different constraints.


//  ww  w  .j  a  va2  s .c om
using System;
using System.Reflection;

public interface ITest {}
public class Base {}
public class Test<T,U> 
    where T : Base, ITest 
    where U : class, new() {}

public class Derived : Base, ITest {}

public class Example
{
    public static void Main()
    {
        Type def = typeof(Test<,>);
        Console.WriteLine("\r\nExamining generic type {0}", def);

        Type[] defparams = def.GetGenericArguments();
        foreach (Type tp in defparams)
        {
            Console.WriteLine(ListGenericParameterAttributes(tp));
        }
    }
    private static string ListGenericParameterAttributes(Type t)
    {
        string retval;
        GenericParameterAttributes gpa = t.GenericParameterAttributes;
        GenericParameterAttributes variance = gpa & GenericParameterAttributes.VarianceMask;

        // Select the variance flags. 
        if (variance == GenericParameterAttributes.None)
            retval = "No variance flag;";
        else
        {
            if ((variance & GenericParameterAttributes.Covariant) != 0)
                retval = "Covariant;";
            else
                retval = "Contravariant;";
        }
        return retval;
    }
}

The code above generates the following result.