crystal macro: reflect

crystal_macro.cr

class A
  def name
    "itang"
  end
end

macro field(obj, name)
  if {{obj}}.responds_to? {{name}}
    {{obj}}.{{name.id}}
  end
end

a = A.new
p field(a, :name)
p field(a, :id)

##output
#"itang"
#nil