26 Mar
2009
26 Mar
'09
12:55 p.m.
On Thu, Mar 26, 2009 at 11:56, Vincent Massol <vincent(a)massol.net> wrote:
Hi,
To start with I propose to model against the plexus annotations but
more simple:
* Component
* Requirement
* Configuration
/**
* Marks a class as a XWiki component.
*/
@Documented
@Retention(RUNTIME)
@Target(TYPE)
@Inherited
public @interface Component
{
Class<?> role();
String hint() default "";
String instantiationStrategy() default "";
}
/**
* Configures a requirement.
*/
@Documented
@Retention(RUNTIME)
@Target({ FIELD, METHOD })
@Inherited
public @interface Requirement
{
Class<?> role() default Object.class;
String hint() default "";
//
// HACK: This is here to support component requirement lists,
which can take a list of hints
//
String[] hints() default {};
}
Note: not sure yet why plexus says it's a hack.
/**
* Marks a field as a configuration element with a default value.
*/
@Documented
@Retention(RUNTIME)
@Target(FIELD)
@Inherited
public @interface Configuration
{
String name() default "";
String value();
}
So for example in the code you'd have:
@Component(role=Parser.class)
public class WikiModelXWikiParser implements Parser...
{
@Requirement
private LinkParser linkParser;
....
wdyt?
Sounds good but I would suggest maybe another way to see it: having an
annotation for each thing. Then it's possible to put the
@ComponentRole annotation on the interface.
That way it's easier to write a component and harder to forget to
register it, it would be a component simply by implementing a
component interface like in:
@ComponentRole(Parser.class)
public interface Parser
{
}
public class DefaultParser implements Parser
{
@Requirement
private LinkParser linkParser;
}
And it is still possible to have a role which is not an interface or
overwrite the role by putting a different @ComponentRole on the
implementation or in a child interface.
And eventually add a way to avoid a class implementing a component
interface to be registered as component (even it's a rare use case I
think)
@ComponentSkip
public class ParserButNotAComponent implements Parser
{
}
I'm still researching.
Thanks
-Vincent
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Thomas Mortagne