Hello all,
I have an idea that I want to run by you all -- a new method on
java.util.function.Function to capture ternary operations.
Here is a mockup of what I wanted to do.
>
> import java.util.function.Function;
>
> @FunctionalInterface
> public interface Function2<I, O> extends Function<I, O>
> {
>
> public static <I, O> Function<I, O> ternary
> (
> Predicate<I> test,
> Function<I, O> trueOutput,
> Function<I, O> falseOutput
> )
> {
>
> return
> (I input) ->
> test.test(input)
> ? trueOutput.apply(input)
> : falseOutput.apply(input)
> ;
>
> }
>
> }
>
I think this is useful for a few reasons.
* This composes, just like the ternary operator itself.
* It pairs well with Function.identity() and method references to clearly
(but concisely) communicate intent.
* Ternary operations are common, so this will find great use by developers
of all sorts.
There is at least one part I don't quite like about this design - what if
one (or both!) of your outputs is not a functional transformation of the
input?
For example, String username = id.isBlank() ? "UNKNOWN" : lookup(id);
Obviously, this is easy to work around - simply ignore the input of the
function. But you lose clarity and simplicity that way. I would put a note
in the javadoc that says that this method should only be used in instances
where both outputs are a functional transformation of the input. That way,
intent is clarified. But if we go that route, maybe this function should
get a better name to capture that? testThenApply? ternaryTransform?
ternaryApply?
Thank you for your time and help!
David Alayachew
