2007/7/12, Alexei Zakharov <[EMAIL PROTECTED]>:
Spark,
I don't see many reasons to couple all persistence delegates into a
single class. IMO "one class to one persistence delegate" model is
obvious and easy to understand. AFAIU RI implements its persistence
delegates in this way. BTW what do you mean by code duplication here?
For example, looking into the implementation for
java_lang_BytePersistenceDelegate & java_lang_DoublePersistenceDelegate.
They both have a instantiate method and an empty initialize method.
The instantiate method of BytePersistenceDelegate is like:
Byte value = (Byte) oldInstance;
return new Expression(oldInstance, Byte.class, "new",new Object[] {
value });
while the instantiate method of DoublePersistenceDelegate is like:
Double value = (Double) oldInstance;
return new Expression(oldInstance, Double.class, "new", new Object[]
{ value }); //$NON-NLS-1$
IMHO, the logic are similar, and can be changed to:
return new Expression(oldInstance, oldInstance.getClass(),
"new", new Object[] { oldInstance });
The situation exist for other primitive type persistence delegate. They are
the PDs I listed in my original post.
The behavior of instantiate() method is unique to each PD and all that
we can do is to create a single class with a big big switch that
includes the code from all our PDs. Do we really want this?
I agree with you that a big switch is not a good method. I think we can put
PrimitiveTypePersistenceDelegate into the persistenceDelegates in class
initializer instead of a big switch:
static PrimitiveTypePersistenceDelegate primitiveTypePD = new
PrimitiveTypePersistenceDelegate();
static {
persistenceDelegates.put(int.class, primitiveTypePD);
persistenceDelegates.put(double.class, primitiveTypePD);
// etc.
}
There is another benefit here: we eliminate type name extraction logic for
primitive type.
IMHO it is
not an Object-Oriented way.
Sorry if I misunderstand your idea. Please explain in more details if so.
Thanks,
2007/7/12, Spark Shen <[EMAIL PROTECTED]>:
> During developing PersistenceDelegate for java.lang.reflect.Field, I
find
> code duplication in many primitive type persistence delegate.
>
> There are 8 primitiveType persistenceDelegate:
> java_lang_BooleanPersistenceDelegate
> java_lang_BytePersistenceDelegate
> java_lang_CharacterPersistenceDelegate
> java_lang_DoublePersistenceDelegate
> java_lang_FloatPersistenceDelegate
> java_lang_IntegerPersistenceDelegate
> java_lang_LongPersistenceDelegate
> java_lang_ShortPersistenceDelegate
>
> Each of the 8 class has two method: instantiate & initialize, and the
logic
> of the 2 methods are similar.
> IMO, we could use one PrimitiveTypePersistenceDelegate instead to reduce
> code duplication.
> --
> Spark Shen
> China Software Development Lab, IBM
>
--
Alexei Zakharov,
Intel ESSD
--
Spark Shen
China Software Development Lab, IBM
