Value Dropdown Attribute

[ValueDropdown("TextureSizes")]
public int SomeSize1;

[ValueDropdown("FriendlyTextureSizes")]
public int SomeSize2;

[ValueDropdown("FriendlyTextureSizes", AppendNextDrawer = true, DisableGUIInAppendedDrawer = true)]
public int SomeSize3;

[ValueDropdown("GetListOfMonoBehaviours", AppendNextDrawer = true)]
public MonoBehaviour SomeMonoBehaviour;

[ValueDropdown("KeyCodes")]
public KeyCode FilteredEnum;

[ValueDropdown("TreeViewOfInts", ExpandAllMenuItems = true)]
public List<int> IntTreview = new List<int>() { 1, 2, 7 };

[ValueDropdown("GetAllSceneObjects", IsUniqueList = true)]
public List<GameObject> UniqueGameobjectList;

[ValueDropdown("GetAllSceneObjects", IsUniqueList = true, DropdownTitle = "Select Scene Object", DrawDropdownForListElements = false, ExcludeExistingValuesInList = true)]
public List<GameObject> UniqueGameobjectListMode2;

private IEnumerable TreeViewOfInts = new ValueDropdownList<int>()
{
    { "Node 1/Node 1.1", 1 },
    { "Node 1/Node 1.2", 2 },
    { "Node 2/Node 2.1", 3 },
    { "Node 3/Node 3.1", 4 },
    { "Node 3/Node 3.2", 5 },
    { "Node 1/Node 3.1/Node 3.1.1", 6 },
    { "Node 1/Node 3.1/Node 3.1.2", 7 },
};

private IEnumerable<MonoBehaviour> GetListOfMonoBehaviours()
{
    return GameObject.FindObjectsOfType<MonoBehaviour>();
}

private static IEnumerable<KeyCode> KeyCodes = Enumerable.Range((int)KeyCode.Alpha0, 10).Cast<KeyCode>();

private static IEnumerable GetAllSceneObjects()
{
    Func<Transform, string> getPath = null;
    getPath = x => (x ? getPath(x.parent) + "/" + x.gameObject.name : "");
    return GameObject.FindObjectsOfType<GameObject>().Select(x => new ValueDropdownItem(getPath(x.transform), x));
}

private static IEnumerable GetAllScriptableObjects()
{
    return UnityEditor.AssetDatabase.FindAssets("t:ScriptableObject")
        .Select(x => UnityEditor.AssetDatabase.GUIDToAssetPath(x))
        .Select(x => new ValueDropdownItem(x, UnityEditor.AssetDatabase.LoadAssetAtPath<ScriptableObject>(x)));
}

private static IEnumerable GetAllSirenixAssets()
{
    var root = "Assets/Plugins/Sirenix/";

    return UnityEditor.AssetDatabase.GetAllAssetPaths()
        .Where(x => x.StartsWith(root))
        .Select(x => x.Substring(root.Length))
        .Select(x => new ValueDropdownItem(x, UnityEditor.AssetDatabase.LoadAssetAtPath<UnityEngine.Object>(root + x)));
}

private static IEnumerable FriendlyTextureSizes = new ValueDropdownList<int>()
{
    { "Small", 256 },
    { "Medium", 512 },
    { "Large", 1024 },
};

private static int[] TextureSizes = new int[] { 256, 512, 1024 };