On using Optional: to me, it was mostly a documentation issue, making it easier to no longer have to worry about whether some method will return null or whether someone will pass null to a method. It also made it easier to remember to actually check for the existence of something before using it. We also used Guava's Optional which is much more pleasant to work with than the JDK's Optional.
On Thu, Oct 10, 2019 at 5:46 PM Gian Merlino <g...@apache.org> wrote: > For reference, a (brief) earlier conversation about this: > https://github.com/apache/incubator-druid/issues/4275, which links to > https://github.com/apache/incubator-druid/pull/4254#discussion_r116628607, > which links to > > https://stackoverflow.com/questions/26327957/should-java-8-getters-return-optional-type/26328555#26328555 > . > > I really enjoyed programming with Scala's Option type, back when I had > spend a couple of years writing Scala code. They are awesome. Java > Optionals are sadly not quite as good, especially in ecosystem support > (they're not adopted very well in libraries or in the jdk itself) but also > in functionality (in Scala they're tightly integrated into the collections > library, which allows for some nice idioms). > > After that Scala break, when I came back to Java I wrote a lot of the > indexing service module. You can tell because it has Guava Optionals > everywhere. I mostly used it the way that Goetz recommended, as a method > return type in commonly used interfaces or utility methods. It was a bit > clunky but it was overall nice. I don't regret it. But now I mostly don't > use them anymore, and started using null-returns (with @Nullable > annotations) instead since it jives better with the rest of the codebase. > > Jad, or anyone else, have you worked on Java codebases where Optional was > heavily used? What was the experience like? > > Also, has anyone had experience introducing a preference for Optionals into > a large pre-existing codebase? > > On Wed, Oct 9, 2019 at 12:46 PM Jad Naous <jad.na...@imply.io> wrote: > > > Sir Tony Hoare on inventing null while working on ALGOL (from wikipedia > > below): > > > > Speaking at a software conference called QCon London > > <https://qconlondon.com/> in 2009, he apologised for inventing the null > > reference <https://en.wikipedia.org/wiki/Null_pointer>:[23] > > <https://en.wikipedia.org/wiki/Tony_Hoare#cite_note-23> > > > > I call it my billion-dollar mistake. It was the invention of the null > > reference in 1965. At that time, I was designing the first comprehensive > > type system for references in an object oriented language (ALGOL W > > <https://en.wikipedia.org/wiki/ALGOL_W>). My goal was to ensure that all > > use of references should be absolutely safe, with checking performed > > automatically by the compiler. But I couldn't resist the temptation to > put > > in a null reference, simply because it was so easy to implement. This has > > led to innumerable errors, vulnerabilities, and system crashes, which > have > > probably caused a billion dollars of pain and damage in the last forty > > years. > > > > How about we stop passing nulls around as method arguments, field values, > > return values, etc and use Optional instead? Benefits: > > - No more NPEs > > - Better documentation through code > > - Less mistakes > > > > I'm not suggesting we go rewrite everything, but rather just starting to > > only return and accept Optionals in methods/constructors/etc. > > > > Jad. > > > > -- > > Jad Naous > > Imply | VP R&D > > 650-521-3425 > > jad.na...@imply.io > > > -- Jad Naous Imply | VP R&D 650-521-3425 jad.na...@imply.io
