alternatives to multiple if/elses

alternatives_to_conditionals.rb

# Using a hash

def classes_for(path)
  classes = {
    'facilities' => %w(instalaciones listado),
    'offers'     => %w(oferta academica),
    'teachers'   => %w(claustro),
    'news'       => %w(actualidad),
    'agenda'     => %w(actualidad)
  }
  
  classes.key?(path) ? classes[path] : []
end


# Moving the conditionals to "matchers"
# Consider the following code

def teach(person)
  if person.age < 1.year || some_complex_condition
    # the way babies are taught...
  elsif person.age.between(7, 14) || some_complex_condition
    # the way youngsters are taught...
  elsif person.age > 18 || some_other_complex_condition
    # the way adults are taught...
  end
end

# The solution above may be okay for simple code or for code that is not expected to be changed often.
# In order to make it more extensible or able to add conditions in runtime, it may be worth to split
# the responsibilities.


class BabiesTeacher
  def can_teach?(person)
    person.age < 1.year || some_complex_condition
  end
  
  def teach(person)
    # the way babies are taught...
  end
end

class YoungstersTeacher
  def can_teach?(person)
    person.age.between(7, 14) || some_complex_condition
  end
  
  def teach(person)
    # the way youngsters are taught...
  end
end

class AdultsTeacher
  def can_teach?(person)
    person.age > 18 || some_other_complex_condition
  end
  
  def teach(person)
    # the way adults are taught...
  end
end


teachers = [BabiesTeacher.new, YoungstersTeacher.new, AdultsTeacher.new]
teachers.each do |teacher|
  teacher.teach(person) if teacher.can_teach?(person)
end