Installation

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$ composer require symfony/debug

Alternatively, you can clone the https://github.com/symfony/debug repository.

Usage

The Debug component provides several tools to help you debug PHP code. Enabling them all can be done by calling the static method Debug::enable():

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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.

Enabling the Error Handler

The ErrorHandler class catches PHP errors and converts them to exceptions (of class ErrorException or FatalErrorException for PHP fatal errors):

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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:

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use Symfony\Component\Debug\ExceptionHandler;

ExceptionHandler::register();

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.

To activate the DebugClassLoader, call its static enable() method:

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use Symfony\Component\Debug\DebugClassLoader;

DebugClassLoader::enable();