Originally posted by @asterite in https://github.com/crystal-lang/crystal/issues/10281#issuecomment-766358669

string_enum.cr

macro string_enum(name, &block)
  enum {{name}}
    {% for exp in block.body.expressions %}
      {% if exp.is_a?(Assign) %}
        {{exp.target}}
      {% else %}
        {{exp}}
      {% end %}
    {% end %}

    def to_s
      case self
        {% for exp in block.body.expressions %}
          {% if exp.is_a?(Assign) %}
            in {{exp.target}}
              {{exp.value}}
          {% end %}
        {% end %}
      end
    end
  end
end

string_enum Numbers do
  One   = "1"
  Two   = "2"
  Three = "3"

  def hello
    "Hello!"
  end
end

puts Numbers::One
puts Numbers::Two
puts Numbers::Three

puts Numbers::One.hello