fallback

fallback.rb

#------------------------------------------------------------------------
def Fallback(lambda, &fallback)
  fallback ||= -> { raise }
  begin
    lambda.call()
  rescue
    fallback.call()
  end
end

require 'active_support/core_ext'

def date_of_birth(age:)
  birth_date = Date.today - age.year
  birth_date.year 
end

p Fallback -> { date_of_birth(age: 25) }        
p Fallback -> { date_of_birth(age: '25') } { 'probably before 2000' }
p Fallback -> { date_of_birth(age: '25') }

# 1989
# "probably before 2000"
# fallback.rb:13:in `date_of_birth': undefined method `year' for "25":String (NoMethodError)