Ruby finders

person.rb

class Person
  @all = []
  
  def self.all
    @all
  end
  
  def self.where(conditions)
    all.select do |person|
      conditions.map do |k, v|
        v = "'#{v}'" if v.is_a? String
        person.instance_eval [k, v].join
      end.all?
    end
  end
  
  attr_reader :name, :age
  
  def initialize(name, age)
    @name, @age = name, age
    Person.all << self
  end
end

marc   = Person.new('marc', 23)
sophie = Person.new('sophie', 24)

Person.where('name==' => 'marc', 'age<=' => 23) # => [marc]
Person.where('age<=' => 24)                     # => [marc, sophie]