restore_error_handler()

(PHP 4 >= 4.0.1, PHP 5, PHP 7)

还原之前的错误处理函数

说明

restore_error_handler(void): bool

在使用set_error_handler()改变错误处理函数之后，此函数可以用于还原之前的错误处理程序(可以是内置的或者也可以是用户所定义的函数)。

返回值

该函数总是返回TRUE。

范例

Example #1restore_error_handler()范例

如果是unserialize()导致了一个错误，接下来会恢复原来的错误处理函数。

<?php
function unserialize_handler($errno, $errstr)
{
    echo "Invalid serialized value.\n";
}
$serialized = 'foo';
set_error_handler('unserialize_handler');
$original = unserialize($serialized);
restore_error_handler();
?>

以上例程会输出：

Invalid serialized value.

参见

• error_reporting() 设置应该报告何种 PHP 错误
• set_error_handler() 设置用户自定义的错误处理函数
• restore_exception_handler() 恢复之前定义过的异常处理函数。
• trigger_error() 产生一个用户级别的 error/warning/notice 信息

Isolde is kind of wrong. The error handlers are stacked with set_error_handler(), and popped with restore_error_handler(). Here i put an example:
<?php
  mysql_connect("inexistent"); //Generate an error. The actual error handler is set by default
  function foo1() {echo "<br>Error foo1<br>";}
  function foo2() {echo "<br>Error foo2<br>";}
  function foo3() {echo "<br>Error foo3<br>";}
  
  set_error_handler("foo1");  //current error handler: foo1
  set_error_handler("foo2");  //current error handler: foo2
  set_error_handler("foo3");  //current error handler: foo3
  
  mysql_connect("inexistent");  
  restore_error_handler();    //now, current error handler: foo2
  mysql_connect("inexistent");   
  restore_error_handler();    //now, current error handler: foo1
  mysql_connect("inexistent"); 
  restore_error_handler();    //now current error handler: default handler
  mysql_connect("inexistent");
  restore_error_handler();    //now current error handler: default handler (The stack can't pop more)
?>

Calling restore_error_handler from within an error handler might result in unexpected behaviour:
<?php
error_reporting(0);
set_error_handler('handleError1');
trigger_error('1-stack:h1');
set_error_handler('handleError2');
trigger_error('2-stack:h1,h2');
trigger_error('6-stack:h1,h2');
trigger_error('7-stack:h1,h2');
function handleError1($code, $message, $file = '', $line = 0, $context = array())
{
  echo __METHOD__ . ' ' . $message . PHP_EOL;
}
function handleError2($code, $message, $file = '', $line = 0, $context = array())
{
  trigger_error('3-DEFAULT'); // This will use the php's default error handler
  echo __METHOD__ . ' ' . $message . PHP_EOL;
  set_error_handler('handleError3');
  trigger_error('4-stack:h1,h2,h3');
  restore_error_handler(); // This will restore the handleError1 instead of the default error handler
  trigger_error('5-DEFAULT');
}
function handleError3($code, $message, $file = '', $line = 0, $context = array())
{
  echo __METHOD__ . ' ' . $message . PHP_EOL;
}
?>
The above code will output:
handleError1 1-stack:h1
handleError2 2-stack:h1,h2
handleError3 4-stack:h1,h2,h3
handleError1 5-DEFAULT
handleError1 6-stack:h1,h2
handleError1 7-stack:h1,h2
The following workaround can be used:
<?php
error_reporting(0);
set_error_handler('handleError1');
trigger_error('1-stack:h1');
set_error_handler('handleError2');
trigger_error('2-stack:h1,h2');
trigger_error('6-stack:h1,h2');
trigger_error('7-stack:h1,h2');
function handleError1($code, $message, $file = '', $line = 0, $context = array())
{
  echo __METHOD__ . ' ' . $message . PHP_EOL;
}
function handleError2($code, $message, $file = '', $line = 0, $context = [])
{
  restore_error_handler(); // This will restore the previous error handler
  set_error_handler('count', 0); // Set a dummy method for error handling, it will never be called because $error_type = 0
  try
  {
    trigger_error('3-DEFAULT');
    echo __METHOD__ . ' ' . $message . PHP_EOL;
    set_error_handler('handleError3');
    trigger_error('4-stack:h1,h2,h3');
    restore_error_handler();
    trigger_error('5-DEFAULT');
  }
  finally
  {
    restore_error_handler(); // Restore the previous error handler
    set_error_handler('handleError2'); // Set the current error handler again
  }
}
function handleError3($code, $message, $file = '', $line = 0, $context = [])
{
  echo __METHOD__ . ' ' . $message . PHP_EOL;
}
?>
which will output:
handleError1 1-stack:h1
handleError2 2-stack:h1,h2
handleError3 4-stack:h1,h2,h3
handleError2 6-stack:h1,h2
handleError3 4-stack:h1,h2,h3
handleError2 7-stack:h1,h2
handleError3 4-stack:h1,h2,h3

Works also for restoring nested error handlers:
<?php
error_reporting(E_ALL);
echo '<pre>';
set_error_handler(function($errno, $errstr, $errfile, $errline, array $errcontext) {
  echo 'ErrorHandler 1: ' , $errstr , PHP_EOL;
});
trigger_error('Error 1');
set_error_handler(function($errno, $errstr, $errfile, $errline, array $errcontext) {
  echo 'ErrorHandler 2: ' , $errstr , PHP_EOL;
});
trigger_error('Error 2');
restore_error_handler();
trigger_error('Error 3');
restore_error_handler();
trigger_error('Error 4');
?>

As the docs say, restore_error_handler() revert to the *previous error handler*... even if it is the same. A bug made me set twice my custom error handler and later when I was calling restore_error_handler() to restore the built-in handler nothing seemed to happen... this puzzled me for a while!