WriteAttributePtr attribute = this->attribute_try_get_for_write(attribute_name);

/* If the attribute doesn't exist, make a new one with the correct type. */
if (!attribute) {
  this->attribute_try_create(attribute_name, domain, data_type);
  attribute = this->attribute_try_get_for_write(attribute_name);
  return OutputAttributePtr(std::move(attribute));
}

/* If an existing attribute has a matching domain and type, just use that. */
if (attribute->domain() == domain && attribute->cpp_type() == *cpp_type) {
  return OutputAttributePtr(std::move(attribute));
}

/* Otherwise create a temporary buffer to use before saving the new attribute. */