Bikeshed opportunity: compose vs composeWith (original) (raw)

Brian Goetz brian.goetz at oracle.com
Mon Nov 26 14:56:17 PST 2012

This would be cool to read, but is a different animal.

people.sortBy(Person::getLast).thenBy(Person::getFirst)

Right. See exchange last week about the combinatorial explosion when we tried this.

We use the word "chain" on our Comparators static utility class in GS Collections with varargs. But since you are adding this method to Comparator, not sure if chain or chainWith would be a good name.

Seems a possibility.

What about this?

people.sort(comparing(Person::getLast).thenBy(Person::getFirst))

At first I thought this was "same as above", but now that I think about it more it is possible. This would involve overloading:

thenBy(Comparator)

with

thenBy(Function<T,U extends Comparable>) thenBy(IntFunction)

in Comparator.

It also looks OK outside the sort example:

Comparator byFirstLast = byLast.thenBy(Person::getFirst);

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