com.smartgwt.client.bean

Interface BeanValueType.MetaFactory

Enclosing class:

BeanValueType<ValueType>

public static interface BeanValueType.MetaFactory

Interface used to trigger the generation and registration of reflection metadata for argument types.

In order to use BeanValueType to convert values to a type, you need to create the correct kind of BeanValueType for each type, which sometimes involves code generation. This is all automatic for types required by BeanFactory. However, if want to use BeanValueType outside of BeanFactory, then you can use BeanValueType.MetaFactory for specific types.

Usage is most easily explained with an example. First, you define an interface. (Note that it can be an inner interface.)

 public interface MyMetaFactory extends BeanValueType.MetaFactory {
     BeanValueType<Integer[]> getIntegerArrayValueType();
     BeanValueType<Canvas> findMeTheCanvasValueType();
 }

... and then you trigger the generation process:

 GWT.create(MyMetaFactory.class);

Each function in the interface you define will result in the creation of the BeanValueType for one type ... so, in this case, we would end up with BeanValueTypes for Integer arrays and Canvas. The rules are as follows:

1. The interface must extend BeanValueType.MetaFactory
2. The return type for each function must be BeanValueType, with a generic type that is the type you want to be able to convert to.
3. The function must take no arguments.
4. The name of the function doesn't matter.

If you want, you can keep a reference to the results of the GWT.create(), and call the functions:

 MyMetaFactory metaFactory = GWT.create(MyMetaFactory.class);
 BeanValueType<Integer[]> integerArrayType = myMetaFactory.getIntegerArrayValueType();
 Integer[] intArray = integerArrayType.convertFrom(new String[] {"7", "8"});

However, you don't have to do that ... you can ignore the results of GWT.create() and just use the BeanValueType static API:

 GWT.create(MyMetaFactory.class);
 Integer[] intArray = BeanValueType.convertFrom(Integer[].class, new String[] {"7", "8"});

Note that the call to GWT.create() must occur at run-time before the types are used. However, you can modularize by creating some types first and others later, as long as each BeanValueType is created before being used.

If you just need to convert to basic types -- int, long, float, double, boolean, Integer, Long, Float, Double, Boolean and String, then you can call BeanValueType.registerBasicValueTypes() instead of using GWT.create().