Logger

Crystal provides a logger to help developer tracking informations.
The logger is provided in two different ways based on the PHP version that's used, if it's on PHP 5 the logger is provided as a function, if it's on PHP 7 or newer versions it's provided as an object with an interface similar to the interface provided by PSR-3.

Both the implementations use syslog, so you can manage the implementation through openlog.

The logger allows also placeholders inside the message, like defined in this section of PSR-3: for each key in the context, all the placeholders defined as {key} inside the message will be replaced with the related context value.

PHP 5 version

$mf(function () use ($mf) {
    $logger = $mf('logger');

    $logger('info', 'lorem {placeholder}', array(
        'foo' => true,
        'placeholder' => 'ipsum',
    ));
    $logger('debug', 'dolor sit amet');
});

PHP 7+ version

$mf(function () use ($mf) {
    $logger = $mf('logger');

    $logger->info('lorem ipsum', [
        'foo' => true,
    ]);
    $logger->debug('dolor sit amet');
});

If the logger is used in PHP 7+, there are other utilities available.

Shared Context

$mf(function () use ($mf) {
    $logger = $mf('logger');

    $logger->addContext('session_id', session_id());

    // replace all the other keys in the shared context
    // $logger->setContext(['session_id' => session_id()]);

    // reset the shared context
    // $logger->resetContext();

    // to remove some keys from shared context
    // $logger->unsetContext('foo', 'bar');

    // if you need to know what's in the shared context
    // $context = $logger->getContext();

    // 'session_id' will be added implicitly to the context
    $logger->info('lorem ipsum', [
        'foo' => true,
    ]);
});

Custom Implementation

If you need to redefine the logger implementation (e.g. for a custom logging), you can redefine the logger implementation with the setImplementation method and it takes the arguments:

• level: string: which could be one of these levels
• message: string: the logging message
• context: array: an optional array of context, this could be an empty array or could contain the union of shared and local context data

$mf(function () use ($mf) {
    $logger = $mf('logger');

    $logger->addContext('bar', 'test');

    $logger->setImplementation(function ($level, $message, $context) {
        echo sprintf("%s: %s - %s\n", $level, $message, json_encode($context));
    });

    $logger->info('lorem ipsum', array(
        'foo' => true,
    ));
    $logger->debug('dolor {placeholder} amet', array(
        'bar' => 1,
        'placeholder' => 'sit',
    ));
    $logger->emergency('consectetur adipisci elit');
});

in this case output will be

info: lorem ipsum - {"bar":"test","foo":true}
debug: dolor sit amet - {"bar":1,"placeholder":"sit"}
emergency: consectetur adipisci elit - {"bar":"test"}