Groovy Map Minus
06 June 2017
Groovy is relatively intuitive for me: I can usually guess a method or operator and find it works as I had guessed.
Removing a key/value by the key
from a Map conveniently
eludes me though.
I always guess that I should be able
to minus a key from a Map
to produce a new Map
with that entry /value removed.
That doesn’t work,
so I needed to invent my own.
I still not sure how to practically
apply it everywhere though,
or if it’s even worthwhile.
In practice,
I always end up writing the findAll inline.
@Category(Map)
class MapMinus {
Map minus(Collection keys) {
this.findAll { k, v -> ! (k in keys) }
}
Map minus(Object key) {
this - [key]
}
}
use (MapMinus) {
assert [b: 2, c: 3,] == [a: 1, b: 2, c: 3,] - 'a'
assert [b: 2, c: 3,] == [a: 1, b: 2, c: 3,] - ['a']
}