foo.cr

abstract class Foo
  VERBS = %w(GET POST PUT)

  {% for method in ::Foo::VERBS %}
    macro {{ method.downcase.id }}(*args, **params)
      \{% params[:via] = {{ method.downcase }} %}
      match(\{{*args}}, \{{**params}})
    end
  {% end %}

  def self.match(*args, **params)
    puts args, params
  end
end

class Bar < Foo
  get "/path", to: "X"
end

output.log

{"/path"}
{to: "X", via: "get"}