It is not possible to extend enums nor annotations. And as the question
here is about the use of @AuthorizeInstantiation, there's no way to
declare MyEnum[], of course :-)
So, the only way, for now, to have type-safety is using that
Class-thing. I don't vote for this though. A simple class with String
constants does de job quite well. :-D
James Carman wrote:
But, you can declare the values "property" to be of type MyEnum[]. Is what
we're really looking for here the ability to extend an enum (if that even
makes sense)? I've often thought it would be nice if I could add stuff to
an enum from the outside. But, that kind of goes against the idea of an
enum, doesn't it?
On Thu, Dec 4, 2008 at 11:51 PM, Bruno Borges <[EMAIL PROTECTED]>wrote:
Well... you can't do this:
@Foo(values={MyEnum.FOO, MyEnum.BAR});
@interface Foo {
Object[] values() default {};
}
James Carman wrote:
What do you mean by "Enums as Objects"?
On Thu, Dec 4, 2008 at 11:11 PM, Bruno Borges <[EMAIL PROTECTED]
wrote:
Well... You don't have to create one java file for each class. You can
put
all of them on the same file, like:
public final class MyAppRoles {
private MyAppRoles() {}
public static final class Admin extends Role {
private Admin() {}
}
public static final class User extends Role {
private User() {}
}
}
Note that this is really type-safe, and these classes will never be
instantiated.
But, I'm not defending that we should change that. I'm just showing a
possibility. :-)
I really did't understand why Sun decided to reject Enums as Objects in
this context of annotations.
cheers,
Bruno
James Carman wrote:
I don't know about this. It would work (and break existing code, unless
you
use something other than value for the annotation). I don't know if I
would
want to have to create a new class for each role in my project. Yes, it
would be a small price to pay, but it just feels wrong.
On Thu, Dec 4, 2008 at 10:33 PM, Bruno Borges <[EMAIL PROTECTED]
wrote:
I've found a way to implement a type-safe check for this. Here it goes:
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@AuthorizeInstantiation(value = { User.class, Admin.class })
public class EnumAnnotation {
}
@Retention(RetentionPolicy.RUNTIME)
@Target( { ElementType.PACKAGE, ElementType.TYPE })
@Documented
@Inherited
@interface AuthorizeInstantiation {
Class<? extends Role>[] value() default {};
}
class Role {
}
class User extends Role {
}
class Admin extends Role {
}
So, the only thing that must change is the annotation
@AuthorizeInstantiation, to accept classes that extends roles.
Thoughts anyone?
cheers,
Bruno
Bruno Borges wrote:
You simply can't do that because the nature of Annotations.
Even if AuthorizeInstantiation's values were of type Object[] you
wouldn't
be able to do that with Enums.
You will have to use Strings.
Although there's some hack you can make using Java 6 to accomplish
what
you want. If you are interested, take a look at this link:
http://www.iam.unibe.ch/~akuhn/blog/2008/roman-numerals-in-your-java/<http://www.iam.unibe.ch/%7Eakuhn/blog/2008/roman-numerals-in-your-java/>
<
http://www.iam.unibe.ch/%7Eakuhn/blog/2008/roman-numerals-in-your-java/
<
http://www.iam.unibe.ch/%7Eakuhn/blog/2008/roman-numerals-in-your-java/
Good luck!!
Cheers,
Bruno
miro wrote:
I am using this @AuthorizeInstantiation (wicket authetication
annotation)
in my pages , the code for this annotation
@Retention(RetentionPolicy.RUNTIME)
@Target( { ElementType.PACKAGE, ElementType.TYPE })
@Documented
@Inherited
public @interface AuthorizeInstantiation {
/**
* Gets the roles that are allowed to take the action.
* * @return the roles that are allowed. Returns a zero length
array by
default
*/
String[] value() default {};
}
I created my enum with representing authorities
public enum Authorities {
LIASION_OFFICER,
GRANTS_OFFICER,
PROGRAM_ANALYST,
ADMIN;
}
I am trying to use AuthorizeInstantiation in my page here an
example
@AuthorizeInstantiation(value={Authorities.LIASION_OFFICER.name()})
public class HomePage extends BasePage {
this line does not compile, I get the error
The value of annotation attribute AuthorizeInstantiation .value must
be
a
constant expression .please help me resolve this .
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