C# 정확한 Type 의 비교 ( IsAssignableFrom vs is )

 var iWorldEquipment = this.controller.GetWorldInterfaceByType(typeof(IWorldEquipment)) as IWorldEquipment;

   public IWorld GetWorldInterfaceByType(System.Type worldInterfaceType)   //IWorldEquipment

    {

        Debug.LogFormat("<color=yellow>{0}</color>", worldInterfaceType);

        var enumerator = this.worldIterator.GetEnumerator();

        var a = worldInterfaceType is IWorldEquipment;

        Debug.Log(a);

        var b = worldInterfaceType.GetType().Equals(typeof(IWorldEquipment));

        Debug.Log(b);

        var c = worldInterfaceType.IsAssignableFrom(typeof(IWorldEquipment));

        Debug.Log(c);

        var d = worldInterfaceType.Equals(typeof(IWorldEquipment));

        Debug.Log(d);

        return null;

    }

C# 정확한 Type 의 비교 ( IsAssignableFrom vs is )

int a;

(a is int)

이런 간단한 타입 비교는 is 가 쉽고 간편하다.

다만 단순 비교로는 타입체크하기 힘든 경우들이 있다.

예를들어 Generic 을 사용 한 타입들, ex) List<T>, Dictionary<T,K> 등등

또는 다차원 배열들 ex) int[3,5] 등등

이런 경우 사용하는 IsAssignableFrom 라는 함수 가 있다. 사용법은 아래와 같다.

private void DoSomethingWithFields<T>(T obj)
{
    // Go through all fields of the type.
    foreach (var field in typeof(T).GetFields())
    {
        var fieldValue = field.GetValue(obj);

        // You would probably need to do a null check
        // somewhere to avoid a NullReferenceException.

        // Check if this is a list/array
        if (typeof(IList).IsAssignableFrom(field.FieldType))
        {
            // By now, we know that this is assignable from IList, so we can safely cast it.
            foreach (var item in fieldValue as IList)
            {
                // Do you want to know the item type?
                var itemType = item.GetType();

                // Do what you want with the items.
            }
        }
        else
        {
            // This is not a list, do something with value
        }
    }
}

아래는 MSDN 에 나와있는 예제이다.

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using System; using System.Collections.Generic; class Program { public static void Main() { // Demonstrate classes: Console.WriteLine("Defned Classes:"); Room room1 = new Room(); Kitchen kitchen1 = new Kitchen(); Bedroom bedroom1 = new Bedroom(); Guestroom guestroom1 = new Guestroom(); MasterBedroom masterbedroom1 = new MasterBedroom(); Type room1Type = room1.GetType(); Type kitchen1Type = kitchen1.GetType(); Type bedroom1Type = bedroom1.GetType(); Type guestroom1Type = guestroom1.GetType(); Type masterbedroom1Type = masterbedroom1.GetType(); Console.WriteLine("room assignable from kitchen: {0}", room1Type.IsAssignableFrom(kitchen1Type)); Console.WriteLine("bedroom assignable from guestroom: {0}", bedroom1Type.IsAssignableFrom(guestroom1Type)); Console.WriteLine("kitchen assignable from masterbedroom: {0}", kitchen1Type.IsAssignableFrom(masterbedroom1Type)); // Demonstrate arrays: Console.WriteLine(); Console.WriteLine("Integer arrays:"); int[] array2 = new int[2]; int[] array10 = new int[10]; int[,] array22 = new int[2, 2]; int[,] array24 = new int[2, 4]; Type array2Type = array2.GetType(); Type array10Type = array10.GetType(); Type array22Type = array22.GetType(); Type array24Type = array24.GetType(); Console.WriteLine("int[2] assignable from int[10]: {0}", array2Type.IsAssignableFrom(array10Type)); Console.WriteLine("int[2] assignable from int[2,4]: {0}", array2Type.IsAssignableFrom(array24Type)); Console.WriteLine("int[2,4] assignable from int[2,2]: {0}", array24Type.IsAssignableFrom(array22Type)); // Demonstrate generics: Console.WriteLine(); Console.WriteLine("Generics:"); // Note that "int?[]" is the same as "Nullable<int>[]" int?[] arrayNull = new int?[10]; List<int> genIntList = new List<int>(); List<Type> genTList = new List<Type>(); Type arrayNullType = arrayNull.GetType(); Type genIntListType = genIntList.GetType(); Type genTListType = genTList.GetType(); Console.WriteLine("int[10] assignable from int?[10]: {0}", array10Type.IsAssignableFrom(arrayNullType)); Console.WriteLine("List<int> assignable from List<Type>: {0}", genIntListType.IsAssignableFrom(genTListType)); Console.WriteLine("List<Type> assignable from List<int>: {0}", genTListType.IsAssignableFrom(genIntListType)); Console.ReadLine(); } } class Room { } class Kitchen : Room { } class Bedroom : Room { } class Guestroom : Bedroom { } class MasterBedroom : Bedroom { } //This code example produces the following output: // // Defned Classes: // room assignable from kitchen: True // bedroom assignable from guestroom: True // kitchen assignable from masterbedroom: False // // Integer arrays: // int[2] assignable from int[10]: True // int[2] assignable from int[2,4]: False // int[2,4] assignable from int[2,2]: True // // Generics: // int[10] assignable from int?[10]: False // List<int> assignable from List<Type>: False // List<Type> assignable from List<int>: False