如何使用@before访问对象变量

Question

在我需要得到的对象中：attributes->id

SimpleXMLElement Object
(
    [@attributes] => Array
        (
            [id] => 30
            [field_type] => text
            [base_type] => text
        )

    [label] => Service
    [nowrap] => 0
    [bold] => 0
    [required] => 0
    [appears_by_default] => 1
    [find_enabled] => 1
    [allow_new_choices] => 0
    [sort_as_given] => 1
    [carrychoices] => 1
    [foreignkey] => 0
    [unique] => 0
    [doesdatacopy] => 1
    [fieldhelp] => SimpleXMLElement Object
        (
        )

    [num_lines] => 1
    [maxlength] => 0
    [append_only] => 0
    [allowHTML] => 0
)

Answer 1

$att = "id";
$fids[] = (string)$field->attributes()->$att;