在尝试使用 __toString() 时，我不断收到以下错误：
可捕获的致命错误：第 36 行的 C:wamp\www\demo.php 中的类地址对象无法转换为字符串
我哪里做错了？
演示.php
echo '<h2>Instantiating Address</h2>';
$address = new Address;
echo '<h2>Empty Address</h2>';
echo '<tt><pre>' . var_export($address, TRUE) . '</pre></tt>';
echo '<h2>Setting properties...</h2>';
$address->street_address_1 = '555 Fake Street';
$address->city_name = 'Townsville';
$address->subdivision_name = 'State';
$address->postal_code = '12345';
$address->country_name = 'United States of America';
echo '<tt><pre>' . var_export($address, TRUE) . '</pre></tt>';
echo '<h2>Displaying address ...</h2>';
echo $address->display();
echo '<h2>Testing magic __get and __set</h2>';
unset($address->postal_code);
echo $address->display();
echo '<h2>Testing Address __construct with an array</h2>';
$address_2 = new Address(array(
'street_address_1' => '123 Phony Ave',
'city_name' => 'Villageland',
'subdivision_name' => 'Region',
'postal_code' => '67890',
'country_name' => 'Canada',
));
echo $address_2->display();
echo '<h2>Address __toString</h2>';
echo $address_2;
?>
oop.php
<!DOCTYPE html>
<html>
<head><title>OOP</title></head>
<body>
<?php
class Address {
public $street_address_1;
public $street_address_2;
public $city_name;
public $subdivision_name;
public $country_name;
protected $_postal_code;
// Primary key of an address
protected $_address_id;
// When the recorded created and last updated
protected $_time_created;
protected $_time_updated;
/*
Constructor
@param array data optional array of property names
*/
function __construct($data = array()) {
$this->_time_created = time();
// Ensure that the address can be populated.
if(!is_array($data)){
trigger_error('Unable to construct address with a ' . get_class($name));
}
// If there is at lease one value, populate the Address with it
if(count($data) > 0) {
foreach($data as $name => $value){
// Special case for protected properties
if(in_array($name, array(
'time_created',
'time_updated',
))){
$name = '_' . $name;
}
$this->$name = $value;
}
}
}
/*
Magic __get
@param string $name
@return mixed
*/
function __get($name){
// Postal code lookup if unset.
if (!$this->_postal_code){
$this->_postal_code = $this->_postal_code_guess();
}
/*
Magin __set.
@param string $name
@param mixed $value
*/
function __set($name, $value){
// Allow anything to set the postal code.
if ('postal_code' == $name){
$this->$name = $value;
return;
}
// Unable to access property; trigger error,
trigger_error('Undefined or unallowed property via __set(): ' . $name);
}
/*
Magic __toString
@return string
*/
function __toString() {
return $this->display();
}
$protected_property_name = '_' . $name;
if(property_exists($this, $protected_property_name)){
return $this->$protected_property_name;
}
// unable to access property; trigger error
trigger_error('Undefined_property via __get: ' . $name);
return NULL;
}
/*
Guess the postal code given the subdivision and city name.
@todo Replace with a database lookup
@return string
*/
protected function _postal_code_guess(){
return 'LOOKUP';
}
/*
display an address in HTML
return string.
*/
function display(){
$output = '';
// Street address
$output .= $this->street_address_1;
if ($this->street_address_2){
$output .= '<br />' . $this->Street_address_2;
}
// City, Subdivision Postal
$output .= '<br />';
$output .= $this->city_name . ', ' . $this->subdivision_name;
$output .= ' ' . $this->postal_code;
// Country
$output .= '<br />';
$output .= $this->country_name;
return $output;
}
}
?>
</body>
</html>