如何使用@Before

Question

在对象访问对象变量i需要得到：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;