Let's make Ternary able to have the same sticky value for each evaluation

[victornoel]

Since most of the cactoos classes are lary-evaluated, sometimes when using Ternary, each call to each of the Scalar it holds in its state will result of a different evaluation of the input value.

For example, the meaning of the following is not very clear:

final Scalar<Integer> scl = new ScalarOf<>(new AtomicInteger(0)::incrementAndGet);
new Ternary<String>(
    () -> scl.value() == 1,
    () -> scl.value() + " equals " + 1,
    () -> "else: " + scl.value()
).value() // returns "2 equals 1"

It is currently possible to write:

final Scalar<Integer> scl = new ScalarOf<>(new AtomicInteger(0)::incrementAndGet);
new Ternary<String>(
    scl.value(),
    i -> i == 1,
    i -> i + " equals " + 1,
    () -> "else: " + i
).value() // returns "1 equals 1"

But it forces us to evaluate scl, which goes against the idea of only composing objects. This means we can't use it in constructors for example where we want to avoid code in them.

Instead, we would like to be able to write:

final Scalar<Integer> scl = new ScalarOf<>(new AtomicInteger(0)::incrementAndGet);
new Ternary<String>(
    scl,
    i -> i == 1,
    i ->  i + " equals " + 1,
    i -> "else: " + i
).value() // return "1 equals 1"

With i being stable the whole value() evaluation.

It would be for example useful to tackle #1460.

[victornoel]

@0crat assign me

[victornoel]

@0crat wait for #1476