module RbSys::Mkmf

def conditional_assign(a, b, export: false, indent: 0)
  if $nmake
    result = +"!IFNDEF #{a}\n#{a} = #{b}\n!ENDIF\n"
    result << export_env(a, b) if export
    result
  else
    "#{"\t" * indent}#{export ? "export " : ""}#{a} ?= #{b}"
  end
end