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Looking at Ruby only:
TL;DR
Use none?
passing it a block with ==
for the comparison:
[1, 2].include?(1)
#=> true
[1, 2].none? { |n| 1 == n }
#=> false
Array#include?
accepts one argument and uses ==
to check against each element in the array:
player = [1, 2, 3]
player.include?(1)
#=> true
Enumerable#none?
can also accept one argument in which case it uses ===
for the comparison. To get the opposing behaviour to include?
we omit the parameter and pass it a block using ==
for the comparison.
player.none? { |n| 7 == n }
#=> true
!player.include?(7) #notice the '!'
#=> true
In the above example we can actually use:
player.none?(7)
#=> true
That’s because Integer#==
and Integer#===
are equivalent. But consider:
player.include?(Integer)
#=> false
player.none?(Integer)
#=> false
none?
returns false
because Integer === 1 #=> true
. But really a legit notinclude?
method should return true
. So as we did before:
player.none? { |e| Integer == e }
#=> true
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