[morph-developer] InstantiatingReflector

[Ben A. <ben...@ac...>]

Hi

We have a requirement to instantiate objects using complex constructors
(not simply no-argument constructors). Essentially we will use parameter
name discovery to retrieve the request parameter names from the
constructor, then source the properties from the input object. We do
this with Dozer quite successfully.

InstantiatingReflector appears the appropriate Morph interface:

public Object newInstance(Class clazz) throws ReflectionException;

This is invoked by the BaseTransformer method:

protected Object createNewInstanceImpl(Class destinationClass,
                             Object source) throws Exception;

I would like to request a change so that InstantiatingReflector is
provided the source object, which we need in order to perform the
desired destination object construction. ie:

public Object newInstance(Class clazz, Object source) throws
ReflectionException;

I don't see this as a major problem, given that existing
InstantiatingReflector implementations can simply ignore the additional
parameter if they don't wish to use it.

Alternately, if backward compatibility were an issue, could we have a
new interface (InstantiatingSourceReflector?) which provided the
interface, and have this new implementation extend
InstantiatingReflector. Then BaseTransformer would detect the type of
instantiating reflector injected and invoke accordingly.

I realise we could simply override the BaseTransformer method, but then
we force concrete inheritance to be used when a strategy pattern already
exists and makes more sense. We just need the strategy to present the
additional parameter.

I'm happy to make this change and provide a patch, but I wanted to check
which approach (or some other) that people preferred.

Thanks
Ben