The php-fig/log repository is a PHP Standards Recommendation (PSR) for logging interfaces. It defines a common interface for logging libraries, allowing for interoperability between different logging implementations in PHP applications. This standard is part of the PHP Framework Interop Group (PHP-FIG) efforts to improve collaboration across PHP projects.

Pros

• Promotes standardization and interoperability among logging libraries
• Simplifies switching between different logging implementations
• Encourages consistent logging practices across PHP projects
• Widely adopted by popular PHP frameworks and libraries

Cons

• Limited to basic logging functionality, may not cover all advanced use cases
• Requires adoption by both library developers and application developers for full benefit
• May introduce an additional layer of abstraction in some cases
• Some existing logging libraries may require adaptation to conform to the standard

Code Examples

1. Basic logging example:

use Psr\Log\LoggerInterface;

class MyClass
{
    private $logger;

    public function __construct(LoggerInterface $logger)
    {
        $this->logger = $logger;
    }

    public function doSomething()
    {
        $this->logger->info('Doing something');
        // ... do something
    }
}

2. Using different log levels:

$logger->emergency('System is down');
$logger->alert('Database connection failed');
$logger->critical('Unexpected error occurred');
$logger->error('Unable to process request');
$logger->warning('Deprecated function used');
$logger->notice('User logged in');
$logger->info('Processing started');
$logger->debug('Variable value: ' . $value);

3. Logging with context:

$logger->error('User {username} not found', ['username' => 'john_doe']);

Getting Started

To use PSR-3 logging in your project:

1. Install a PSR-3 compatible logger (e.g., Monolog):

   composer require monolog/monolog
   

2. Create a logger instance:

   use Monolog\Logger;
   use Monolog\Handler\StreamHandler;
   
   $logger = new Logger('my_logger');
   $logger->pushHandler(new StreamHandler('path/to/your.log', Logger::DEBUG));
   

3. Use the logger in your code:

   $logger->info('Hello, PSR-3 logging!');