CODEWITHSUNDEEP
rubyconditional-statements
Markus Trummer
Markus Trummer

Reputation: 1

Conditional assignment for lists

I know conditional assignments. If the first element evaluates to nil the second element is taken. 

irb(main):004:0> nil || 42
=> 42

Is there a similar concept for lists, such as the second path only gets evaluated if the first is empty not nil.

irb(main):004:0> [] || [1,2,3]
=> [1, 2, 3]

Upvotes: 0

Views: 33

Answers (1)

sawa
sawa

Reputation: 168081

Literally having

[] || [1,2,3]

is useless, so I guess you have it as a certain variable, say a, which might happen to be []. The best you can do is:

a.empty? ? [1, 2, 3] : a

If you are not satisfied with this, and insist along the way you tried, then you need to define additional methods.

class Array
  def tweeze; self unless empty? end
end

a.tweeze || [1, 2, 3]

Upvotes: 2

Related Questions