Rbac Principal with Binding support

Question

I've been maintaining a Rbac helper for some time now. My goal is to provide an easy way to tell the following:

• When does an user have a role
• What can a user do (with those roles)
• Which users have which role in which resources

And I'm pretty happy with my result so far, I can do the following:

var rbac = new RbacSession();
rbac.AddPermission("owner", "Delete");
rbac.UserIsInRoleIf("mantainer", u => u.Identity.Name == "Bob");
rbac.AddUserRoleForTypeIf<string>("Teacher", (user, resource) => resource == "Hello world");

I have been told to get rid of my fluent interface because all of it was wrong.

And my thought was, well yeah... But hey, wouldn't it be really cool if I could support properties to check if a user has a role? If I did I could also support easy binding to WPF Applications. Here follows the implementation

public class RbacPrincipal : IPrincipal, IIdentity
{
 [Browsable(false)]
 public class CanDoAction
 {
 private readonly RbacPrincipal _principal;
 public CanDoAction(RbacPrincipal principal)
 {
 _principal = principal;
 }
 public bool this[string action]
 {
 get
 {
 return _principal._session.Query.IsUserAbleTo(_principal, action);
 }
 }
 public bool this[string action, object resource]
 {
 get
 {
 return _principal._session.Query.IsUserAbleTo(_principal, action, resource);
 }
 }
 }
 [Browsable(false)]
 public class IsUserInRole
 {
 private readonly RbacPrincipal _principal;
 public IsUserInRole(RbacPrincipal principal)
 {
 _principal = principal;
 }
 public bool this[string role]
 {
 get
 {
 return _principal._session.Query.IsUserInRole(_principal, role);
 }
 }
 public bool this[string role, object resource]
 {
 get
 {
 return _principal._session.Query.IsUserInRole(_principal, role, resource);
 }
 }
 }
 private readonly IPrincipal _principal;
 private readonly IRbacSession _session;
 public RbacPrincipal(IPrincipal principal, IRbacSession session)
 {
 _principal = principal;
 _session = session;
 CanDo = new CanDoAction(this);
 Is = new IsUserInRole(this);
 }
 public bool IsInRole(string role)
 {
 //check role on the decorated principal se we avoid stackoverflow
 return _session.Query.IsUserInRole(_principal, role);
 }
 public CanDoAction CanDo { get; private set; }
 public IsUserInRole Is { get; private set; }
 IIdentity IPrincipal.Identity { get { return _principal.Identity; } }
 public string Name { get { return _principal.Identity.Name; } }
 public string AuthenticationType { get { return _principal.Identity.AuthenticationType; } }
 public bool IsAuthenticated { get { return _principal.Identity.IsAuthenticated; } }
}

And an example of the usage of it

var owner = new RbacPrincipal(new Principal
{
 Roles = { "owner", "member", "user" }
}, rbac);
Assert.IsTrue(owner.Is["owner"]);
Assert.IsTrue(owner.Is["member"]);
Assert.IsTrue(owner.CanDo["Delete"]);

I leave the link to full test class on repo here

Now I have one limitation if I use bindings with this. The resources cannot be anything but strings, but at least, and most important I can let you check a role of a user with a binding Is[owner].

Is this it? Did I finally reach the "yayness"?

• svick: I don't understand, why is the syntax owner.Is["owner"] instead of owner.Is("owner") or maybe even better owner.IsInRole("owner")?
• Bruno Costa: @svick If it were a method it couldn't be binded, at least not without help from converters. And notice that I also support owner.IsInRole("owner")