How to pass Object parameter to an user-defined directive?

[Joson Choo]

Hi all,
  I'm new for freemarker. I tried to create my customized directive as
below but could not run it in a right way:


public class TypeSimpleNameDirective implements TemplateDirectiveModel {

   private static final String PARAM_CLAZZ = "clazz";

   @Override
   public void execute(Environment env, Map params, TemplateModel[]
loopVars, TemplateDirectiveBody body) throws TemplateException,
IOException {
      // Check if no parameters were given:
      if (!params.containsKey(PARAM_CLAZZ)) {
         throw new TemplateModelException(
               "typeSimpleName required parameter clazz.");
      }
      if (!(params.get(PARAM_CLAZZ) instanceof ClassDescription)) {
         throw new TemplateModelException(
               "clazz should be a instance of ClassDescription but " +
ClassUtils.getShortClassName(params.get(PARAM_CLAZZ), "null") + " is
given.");
      }
      ClassDescription cls = (ClassDescription) params.get(PARAM_CLAZZ);
  ......
}


And then I used it like this:

<@typeSimpleName clazz=api.returnType></@typeSimpleName>

The api.returnType is ClassDescription.

Then it threw an error:

> clazz should be a instance of ClassDescription but StringModel is given.


Any help is appreciated.