Question

I have an enumeration declared as such

[Flags]
public enum PermissionEnum
{
    [EnumStringValue("None")]
    None = 0x0,
    [EnumStringValue("Create")]
    Create = 0x1,
    [EnumStringValue("Edit")]
    Edit = 0x2,
    [EnumStringValue("View")]
    View = 0x4
}

I subsequently have some linq that attempts to obtain the highest permission available.

List<SecurityRolePermissionView> AvailablePermissions = GetPermissions();

SecurityRolePermissionView HighestPermission = AvailablePermissions.OrderByDescending(o => o.Permission).FirstOrDefault();

With the current enumeration values this seems to do what it suggests it will do. However, I am pretty confident that this code is incorrect but I’m not sure I could explain why or how to achieve a correct implementation.

Either way, could someone please be kind enough to confirm if this is in-fact incorrect (and why) and provide an explanation of how to achieve my desired result?

EDIT: I might not have been clear enough in explaining what my highest permission is. This is a flags enumeration. Therefore it can contain any combination of None, Create, Edit, View. What I am looking to find as the highest is basically Create + Edit + View. If that Fails, Edit + View and lastly View

Answer 1

Enum ordering is the same as the ordering of the enum’s underlying type (C# specification section 7.9.5, “Enumeration operators”). Therefore, this is the order of your possible enum values:

View | Edit | Create ( = 7)
View | Edit          ( = 6)
View | Create        ( = 5)
View                 ( = 4)
Edit | Create        ( = 3)
Edit                 ( = 2)
Create               ( = 1)
None                 ( = 0)

If that ordering fits with your requirements, then your code is correct.