[hibernate-dev] Evolvement of SPIs

[Sanne Grinovero]

On 2 April 2012 10:44, Hardy Ferentschik <hardy at hibernate.org> wrote:
>
> On Apr 2, 2012, at 11:16 AM, Emmanuel Bernard wrote:
>
>> What's your definition of an SPI, in the team we have slightly different ones.
>>
>> In Hibernate search an SPI is targeted at frameworks or hyper advanced user who are willing to integrate or enhance Hibernate Search. Otherwise, they are considered APIs - which includes interfaces you might need to implement like FieldBridge. Hibernate ORM has a different semantic where an API is what the application directly code on.
>
> The HV interpretation of SPI is the same view as in ORM. Imo It makes for a simpler, easier to understand cut between API and SPI.
>
>> For your second question, I have used the idea of an interface combined with an abstract class with success. The interface used by the consumers and the abstract class extended by implementors.
>
> I also think that an abstract class can be beneficial. However, I would not generalize this approach. In the case of the HV interfaces in question we have very simple interfaces
> (single method ones) with a very low likelihood that they will change. I don't think that the abstract base class is needed in this case, especially since it forces you to use inheritance.

I agree as I don't think we have ever set a rule in stone, but it
doesn't force to use inheritance. It's a suggested base class, the
hard contract is still the interface only.

So the implementor can decide to stop inheriting at any time if it
suites best: a base class is indeed not guaranteed to be useful, but
when it's not it doesn't make things harder.

Cheers,
Sanne