If you intend on creating a lot of custom exceptions, you may find this code useful. I've created an interface and an abstract exception class that ensures that all parts of the built-in Exception class are preserved in child classes. It also properly pushes all information back to the parent constructor ensuring that nothing is lost. This allows you to quickly create new exceptions on the fly. It also overrides the default __toString method with a more thorough one.
<?php
interface IException
{
/* Protected methods inherited from Exception class */
public function getMessage(); // Exception message
public function getCode(); // User-defined Exception code
public function getFile(); // Source filename
public function getLine(); // Source line
public function getTrace(); // An array of the backtrace()
public function getTraceAsString(); // Formated string of trace
/* Overrideable methods inherited from Exception class */
public function __toString(); // formated string for display
public function __construct($message = null, $code = 0);
}
abstract class CustomException extends Exception implements IException
{
protected $message = 'Unknown exception'; // Exception message
private $string; // Unknown
protected $code = 0; // User-defined exception code
protected $file; // Source filename of exception
protected $line; // Source line of exception
private $trace; // Unknown
public function __construct($message = null, $code = 0)
{
if (!$message) {
throw new $this('Unknown '. get_class($this));
}
parent::__construct($message, $code);
}
public function __toString()
{
return get_class($this) . " '{$this->message}' in {$this->file}({$this->line})\n"
. "{$this->getTraceAsString()}";
}
}
?>
Now you can create new exceptions in one line:
<?php
class TestException extends CustomException {}
?>
Here's a test that shows that all information is properly preserved throughout the backtrace.
<?php
function exceptionTest()
{
try {
throw new TestException();
}
catch (TestException $e) {
echo "Caught TestException ('{$e->getMessage()}')\n{$e}\n";
}
catch (Exception $e) {
echo "Caught Exception ('{$e->getMessage()}')\n{$e}\n";
}
}
echo '<pre>' . exceptionTest() . '</pre>';
?>
Here's a sample output:
Caught TestException ('Unknown TestException')
TestException 'Unknown TestException' in C:\xampp\htdocs\CustomException\CustomException.php(31)
#0 C:\xampp\htdocs\CustomException\ExceptionTest.php(19): CustomException->__construct()
#1 C:\xampp\htdocs\CustomException\ExceptionTest.php(43): exceptionTest()
#2 {main}
Excepciones
Tabla de contenidos
PHP 5 tiene un modelo de excepciones similar al de otros lenguajes de programación.
Una excepción puede ser lanzada ("thrown"), y atrapada ("catched") dentro de
PHP. El código puede estar dentro de un bloque try para facilitar la captura
de excepciones potenciales. Cada bloque try debe tener al menos un
bloque catch o finally correspondiente.
El objeto lanzado debe ser una instancia de la clase Exception o una subclase de Exception. Intentar lanzar un objeto que no lo sea resultará en un Error Fatal de PHP.
catch
Se pueden usar múltiples bloques catch para atrapar diferentes clases de
excepciones. La ejecución normal (cuando no es lanzada ninguna excepción dentro del bloque
try) continuará después del último bloque catch definido en la sencuencia.
Las excepciones pueden ser lanzadas ("thrown") (o relanzadas) dentro de un bloque catch.
Cuando una excepción es lanzada, el código siguiente a la declaración no será
ejecutado, y PHP intentará encontrar el primer bloque catch coincidente.
Si una excepción no es capturada, se emitirá un Error Fatal de PHP con un
mensaje "Uncaught Exception ..." ("Excepción No Capturada"), a menos que se haya
definido un manejador con set_exception_handler().
finally
En PHP 5.5 y posterior, se puede utilizar un bloque finally después o
en lugar de los bloques catch. El código de dentro del bloque finally siempre se
ejecutará después de los bloques try y catch, independientemente de que se haya
lanzado una excepción o no, y antes de que la ejecución normal continúe.
Notas
Nota:
Las funciones internas de PHP utilizan principalmente la Información de Errores, sólo las extensiones Orientadas a objetos modernas utilizan excepciones. Sin embargo, los errores se pueden traducir a excepciones simplemente con ErrorException.
Sugerencia
La Biblioteca Estádar de PHP (SPL) proporciona un buen número de excepciones internas.
Ejemplos
Ejemplo #3 Lanzar una Excepción
<?php
function inverso($x) {
if (!$x) {
throw new Exception('División por cero.');
}
return 1/$x;
}
try {
echo inverso(5) . "\n";
echo inverso(0) . "\n";
} catch (Exception $e) {
echo 'Excepción capturada: ', $e->getMessage(), "\n";
}
// Continuar la ejecución
echo 'Hola Mundo\n';
?>El resultado del ejemplo sería:
0.2 Excepción capturada: División por cero. Hola Mundo
Ejemplo #4 Manejo de excepciones con un bloque finally
<?php
function inverse($x) {
if (!$x) {
throw new Exception('División por cero.');
}
return 1/$x;
}
try {
echo inverse(5) . "\n";
} catch (Exception $e) {
echo 'Excepción capturada: ', $e->getMessage(), "\n";
} finally {
echo "Primer finally.\n";
}
try {
echo inverse(0) . "\n";
} catch (Exception $e) {
echo 'Excepción capturada: ', $e->getMessage(), "\n";
} finally {
echo "Segundo finally.\n";
}
// Continuar ejecución
echo 'Hola Mundo\n';
?>El resultado del ejemplo sería:
0.2 Primer finally. Excepción capturada: División por cero. Segundo finally. Hola Mundo
Ejemplo #5 Excepciones anidadas
<?php
class MiExcepción extends Exception { }
class Prueba {
public function probar() {
try {
try {
throw new MiExcepción('foo!');
} catch (MiExcepción $e) {
// relanzarla
throw $e;
}
} catch (Exception $e) {
var_dump($e->getMessage());
}
}
}
$foo = new Prueba;
$foo->probar();
?>El resultado del ejemplo sería:
string(4) "foo!"
add a note
User Contributed Notes 15 notes
ask at nilpo dot com ¶
15 years ago
tianyiw at vip dot qq dot com ¶
1 year ago
Easy to understand `finally`.
<?php
try {
try {
echo "before\n";
1 / 0;
echo "after\n";
} finally {
echo "finally\n";
}
} catch (\Throwable) {
echo "exception\n";
}
?>
# Print:
before
finally
exception
Johan ¶
13 years ago
Custom error handling on entire pages can avoid half rendered pages for the users:
<?php
ob_start();
try {
/*contains all page logic
and throws error if needed*/
...
} catch (Exception $e) {
ob_end_clean();
displayErrorPage($e->getMessage());
}
?>
Shot (Piotr Szotkowski) ¶
16 years ago
‘Normal execution (when no exception is thrown within the try block, *or when a catch matching the thrown exception’s class is not present*) will continue after that last catch block defined in sequence.’
‘If an exception is not caught, a PHP Fatal Error will be issued with an “Uncaught Exception …” message, unless a handler has been defined with set_exception_handler().’
These two sentences seem a bit contradicting about what happens ‘when a catch matching the thrown exception’s class is not present’ (and the second sentence is actually correct).
jlherren ¶
10 months ago
As noted elsewhere, throwing an exception from the `finally` block will replace a previously thrown exception. But the original exception is magically available from the new exception's `getPrevious()`.
<?php
try {
try {
throw new RuntimeException('Exception A');
} finally {
throw new RuntimeException('Exception B');
}
}
catch (Throwable $exception) {
echo $exception->getMessage(), "\n";
// 'previous' is magically available!
echo $exception->getPrevious()->getMessage(), "\n";
}
?>
Will print:
Exception B
Exception A
daviddlowe dot flimm at gmail dot com ¶
7 years ago
Starting in PHP 7, the classes Exception and Error both implement the Throwable interface. This means, if you want to catch both Error instances and Exception instances, you should catch Throwable objects, like this:
<?php
try {
throw new Error( "foobar" );
// or:
// throw new Exception( "foobar" );
}
catch (Throwable $e) {
var_export( $e );
}
?>
christof+php[AT]insypro.com ¶
7 years ago
In case your E_WARNING type of errors aren't catchable with try/catch you can change them to another type of error like this:
<?php
set_error_handler(function($errno, $errstr, $errfile, $errline){
if($errno === E_WARNING){
// make it more serious than a warning so it can be caught
trigger_error($errstr, E_ERROR);
return true;
} else {
// fallback to default php error handler
return false;
}
});
try {
// code that might result in a E_WARNING
} catch(Exception $e){
// code to handle the E_WARNING (it's actually changed to E_ERROR at this point)
} finally {
restore_error_handler();
}
?>
Edu ¶
11 years ago
The "finally" block can change the exception that has been throw by the catch block.
<?php
try{
try {
throw new \Exception("Hello");
} catch(\Exception $e) {
echo $e->getMessage()." catch in\n";
throw $e;
} finally {
echo $e->getMessage()." finally \n";
throw new \Exception("Bye");
}
} catch (\Exception $e) {
echo $e->getMessage()." catch out\n";
}
?>
The output is:
Hello catch in
Hello finally
Bye catch out
mlaopane at gmail dot com ¶
6 years ago
<?php
/**
* You can catch exceptions thrown in a deep level function
*/
function employee()
{
throw new \Exception("I am just an employee !");
}
function manager()
{
employee();
}
function boss()
{
try {
manager();
} catch (\Exception $e) {
echo $e->getMessage();
}
}
boss(); // output: "I am just an employee !"
Simo ¶
9 years ago
#3 is not a good example. inverse("0a") would not be caught since (bool) "0a" returns true, yet 1/"0a" casts the string to integer zero and attempts to perform the calculation.
telefoontoestel at nospam dot org ¶
10 years ago
When using finally keep in mind that when a exit/die statement is used in the catch block it will NOT go through the finally block.
<?php
try {
echo "try block<br />";
throw new Exception("test");
} catch (Exception $ex) {
echo "catch block<br />";
} finally {
echo "finally block<br />";
}
// try block
// catch block
// finally block
?>
<?php
try {
echo "try block<br />";
throw new Exception("test");
} catch (Exception $ex) {
echo "catch block<br />";
exit(1);
} finally {
echo "finally block<br />";
}
// try block
// catch block
?>
Tom Polomsk ¶
9 years ago
Contrary to the documentation it is possible in PHP 5.5 and higher use only try-finally blocks without any catch block.
Sawsan ¶
12 years ago
the following is an example of a re-thrown exception and the using of getPrevious function:
<?php
$name = "Name";
//check if the name contains only letters, and does not contain the word name
try
{
try
{
if (preg_match('/[^a-z]/i', $name))
{
throw new Exception("$name contains character other than a-z A-Z");
}
if(strpos(strtolower($name), 'name') !== FALSE)
{
throw new Exception("$name contains the word name");
}
echo "The Name is valid";
}
catch(Exception $e)
{
throw new Exception("insert name again",0,$e);
}
}
catch (Exception $e)
{
if ($e->getPrevious())
{
echo "The Previous Exception is: ".$e->getPrevious()->getMessage()."<br/>";
}
echo "The Exception is: ".$e->getMessage()."<br/>";
}
?>
lscorionjs at gmail dot com ¶
1 year ago
<?php
try {
$str = 'hi';
throw new Exception();
} catch (Exception) {
var_dump($str);
} finally {
var_dump($str);
}
?>
Output:
string(2) "hi"
string(2) "hi"
ilia-yats at ukr dot net ¶
1 year ago
Note some undocumented details about exceptions thrown from 'finally' blocks.
When exception is thrown from 'finally' block, it overrides the original not-caught (or re-thrown) exception. So the behavior is similar to 'return': value returned from 'finally' overrides the one returned earlier. And the original exception is automatically appended to the exceptions chain, i.e. becomes 'previous' for the new one. Example:
<?php
try {
try {
throw new Exception('thrown from try');
} finally {
throw new Exception('thrown from finally');
}
} catch(Exception $e) {
echo $e->getMessage();
echo PHP_EOL;
echo $e->getPrevious()->getMessage();
}
// will output:
// thrown from finally
// thrown from try
?>
Example with re-throwing:
<?php
try {
try {
throw new Exception('thrown from try');
} catch (Exception $e) {
throw new Exception('thrown from catch');
} finally {
throw new Exception('thrown from finally');
}
} catch(Exception $e) {
echo $e->getMessage();
echo PHP_EOL;
echo $e->getPrevious()->getMessage();
}
// will output:
// thrown from finally
// thrown from catch
?>
The same happens even if explicitly pass null as previous exception:
<?php
try {
try {
throw new Exception('thrown from try');
} finally {
throw new Exception('thrown from finally', null, null);
}
} catch(Exception $e) {
echo $e->getMessage();
echo PHP_EOL;
echo $e->getPrevious()->getMessage();
}
// will output:
// thrown from finally
// thrown from try
?>
Also it is possible to pass previous exception explicitly, the 'original' one will be still appended to the chain, e.g.:
<?php
try {
try {
throw new Exception('thrown from try');
} finally {
throw new Exception(
'thrown from finally',
null,
new Exception('Explicitly set previous!')
);
}
} catch(Exception $e) {
echo $e->getMessage();
echo PHP_EOL;
echo $e->getPrevious()->getMessage();
echo PHP_EOL;
echo $e->getPrevious()->getPrevious()->getMessage();
}
// will output:
// thrown from finally
// Explicitly set previous!
// thrown from try
?>
This seems to be true for versions 5.6-8.2.
