rb_define_method (c, "get_file", c_get_file, -1);
rb_define_method (c, "set_file", c_set_file, -1);
rb_define_method (c, "has_alpha?", c_has_alpha_get, 0);
rb_define_method (c, "get_file", c_get_file, -1);
rb_define_method (c, "set_file", c_set_file, -1);
rb_define_method (c, "has_alpha?", c_has_alpha_get, 0);