Magento 2: Quick and dirty Loggers

logger.php

<?php

// https://magento.stackexchange.com/a/92441
// method 1 (< M2.3.5)
$writer = new \Zend\Log\Writer\Stream(BP . '/var/log/test.log');
$logger = new \Zend\Log\Logger();
$logger->addWriter($writer);
$logger->info('Your text message');

// https://magento.stackexchange.com/a/320261
// method 1 (>= M2.3.5)
$writer = new \Laminas\Log\Writer\Stream(BP . '/var/log/test.log');
$logger = new \Laminas\Log\Logger();
$logger->addWriter($writer);
$logger->info('Your text message');




// https://magento.stackexchange.com/a/92439
// method 2
\Magento\Framework\App\ObjectManager::getInstance()
    ->get(\Psr\Log\LoggerInterface::class)->debug('message');




// https://magento.stackexchange.com/a/154592
// method 3 (using DI)
protected $_logger;
public function __construct(
...
\Psr\Log\LoggerInterface $logger
...
) {
    $this->_logger = $logger;
}

public function logExample() {
    //To print string Output in debug.log
    $this->_logger->addDebug('Your Text Or Variables'); 
    
    // To print array Output in system.log
    $this->_logger->log('600', print_r($yourArray, true));
}