Extending SparqlQueryEvaluatorDefault

[dennisvang]

For our project we're thinking about extending the org.eclipse.rdf4j.http.server.readonly.sparql.SparqlQueryEvaluatorDefault class from spring-boot-sparql-web.

However, this class is package-private:

rdf4j/spring-components/spring-boot-sparql-web/src/main/java/org/eclipse/rdf4j/http/server/readonly/sparql/SparqlQueryEvaluatorDefault.java

Line 27 in 37611ab

class SparqlQueryEvaluatorDefault implements SparqlQueryEvaluator {

Moreover, even if we would be able to import this class, we would run into the next problem: We cannot use org.eclipse.rdf4j.http.server.readonly.sparql.QueryTypes either, because it is also package-private.

I don't think a wrapper would help here, so, it looks like the only way to "extend" SparqlQueryEvaluatorDefault would be to copy the relevant code from org.eclipse.rdf4j.http.server.readonly.sparql into our own code base, which, for us, kind of beats the purpose of having the spring-boot-sparql-web dependency.

How would you go about this?

Is there a specific reason why these two classes were not made public (@naturzukunft)?

If not, could they be made public (or protected) in the next release?

[naturzukunft]

Hi,

The rebuild was a while ago. I can't remember the details anymore.

Back then, I rebuilt it to the best of my knowledge and belief so that I could use it. But it's not optimal.

I'm not a fan of inheritance, and my interface implementations are almost always package private ;-)

Almost 10 years ago, I first heard about "share nothing" and was appalled. It occupied my thoughts for many days, and I came to the conclusion that many problems in my then 15 years as a Java developer could be traced back to it.

We often accept dependencies for a handful of lines of code, and our software becomes more complex and dependent as a result.

The dreaded word "redundancy" might not be as bad as it's made out to be.

"QueryTypes" has always scared me. I wanted to rebuild it back then, but it's not that easy!

Making QueryTypes public would mean rdf4j could never refactor it! And since SparqlQueryEvaluatorDefault uses QueryTypes, the same would apply!

I think the implementation of SparqlQueryEvaluator could be improved, and if it were my framework, I wouldn't publish it.

The original code wasn't mine, though; I don't know if it was package private from the start or not.

In my rdf4j abstraction, I have more or less a copy of SparqlQueryEvaluatorDefault & QueryTypes, and I've never managed to refactor it there either ;-o

And after several years and "attempts" (including commons-rdf), I've ended up with my own rdf abstraction layer. It works for me, and I can replace rdf4j with Jena or something else without having to change my projects.

^ I wrote this in a hurry and translated it using Google Translate without checking it over. I hope it’s okay.

If not, could they be made public (or protected) in the next release?
That's sure not my decision ;-)

[dennisvang]

Hi @naturzukunft, thank you so much for the quick and detailed reply!
What you're saying makes perfect sense.
I guess I'll just have to go back to the drawing board. 😅