The Debug Component¶
The Debug component provides tools to ease debugging PHP code.
Installation¶
1 | $ composer require symfony/debug
|
Note
If you install this component outside of a Symfony application, you must
require the vendor/autoload.php
file in your code to enable the class
autoloading mechanism provided by Composer. Read
this article for more details.
Usage¶
The Debug component provides several tools to help you debug PHP code. Enable all of them by calling this method:
1 2 3 | use Symfony\Component\Debug\Debug;
Debug::enable();
|
The enable()
method registers an
error handler, an exception handler and
a special class loader.
Read the following sections for more information about the different available tools.
Caution
You should never enable the debug tools, except for the error handler, in a production environment as they might disclose sensitive information to the user.
Enabling the Error Handler¶
The ErrorHandler
class catches PHP errors
and converts them to exceptions (of class ErrorException
or
FatalErrorException
for PHP
fatal errors):
1 2 3 | use Symfony\Component\Debug\ErrorHandler;
ErrorHandler::register();
|
This error handler is enabled by default in the production environment when the application uses the FrameworkBundle because it generates better error logs.
Enabling the Exception Handler¶
The ExceptionHandler
class catches
uncaught PHP exceptions and converts them to a nice PHP response. It is useful
in debug mode to replace the default PHP/XDebug output with something prettier
and more useful:
1 2 3 | use Symfony\Component\Debug\ExceptionHandler;
ExceptionHandler::register();
|
Note
If the HttpFoundation component is available, the handler uses a Symfony Response object; if not, it falls back to a regular PHP response.
Debugging a Class Loader¶
The DebugClassLoader
attempts to
throw more helpful exceptions when a class isn't found by the registered
autoloaders. All autoloaders that implement a findFile()
method are replaced
with a DebugClassLoader
wrapper.
Using the DebugClassLoader
is done by calling its static
enable()
method:
1 2 3 | use Symfony\Component\Debug\DebugClassLoader;
DebugClassLoader::enable();
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