Moving log formatting out of LogTrait.

This feature becomes limiting very easily, specially when having custom
loggers trying to format the message differently.

src/Log/Engine/BaseLog.php

@@ -15,6 +15,7 @@
 namespace Cake\Log\Engine;
 
 use Cake\Core\InstanceConfigTrait;
+use JsonSerializable;
 use Psr\Log\AbstractLogger;
 
 /**
@@ -74,4 +75,31 @@ abstract class BaseLog extends AbstractLogger {
 		return $this->_config['scopes'];
 	}
 
+/**
+ * Converts to string the provided data so it can be logged. The context
+ * can optionally be used by log engines to interpolate variables
+ * or add additional info to the logged message.
+ *
+ * @param mixed $data The data to be converted to string and logged.
+ * @param array $context Additional logging information for the message.
+ * @return string
+ */
+	protected function _format($data, array $context = []) {
+		if (is_string($data)) {
+			return $data;
+		}
+
+		$object = is_object($data);
+
+		if ($object && method_exists('__toString', $data)) {
+			return (string)$data;
+		}
+
+		if ($object && $object instanceof JsonSerializable) {
+			return json_encode($data);
+		}
+
+		return print_r($data, true);
+	}
+
 }

src/Log/Engine/ConsoleLog.php

@@ -86,6 +86,7 @@ class ConsoleLog extends BaseLog {
  * @return bool success of write.
  */
 	public function log($level, $message, array $context = []) {
+		$message = $this->_format($message, $context);
 		$output = date('Y-m-d H:i:s') . ' ' . ucfirst($level) . ': ' . $message . "\n";
 		return $this->_output->write(sprintf('<%s>%s</%s>', $level, $output, $level), false);
 	}

src/Log/Engine/FileLog.php

@@ -116,6 +116,7 @@ class FileLog extends BaseLog {
  * @return bool success of write.
  */
 	public function log($level, $message, array $context = []) {
+		$message = $this->_format($message, $context);
 		$output = date('Y-m-d H:i:s') . ' ' . ucfirst($level) . ': ' . $message . "\n";
 		$filename = $this->_getFilename($level);
 		if (!empty($this->_size)) {

src/Log/Engine/SyslogLog.php

@@ -104,7 +104,7 @@ class SyslogLog extends BaseLog {
 			$priority = $this->_levelMap[$level];
 		}
 
-		$messages = explode("\n", $message);
+		$messages = explode("\n", $this->_format($message, $context));
 		foreach ($messages as $message) {
 			$message = sprintf($this->_config['format'], $level, $message);
 			$this->_write($priority, $message);

src/Log/Log.php

@@ -312,7 +312,7 @@ class Log {
  *
  * @param int|string $level The severity level of the message being written.
  *    The value must be an integer or string matching a known level.
- * @param string $message Message content to log
+ * @param mixed $message Message content to log
  * @param string|array $scope The scope(s) a log message is being created in.
  *    See Cake\Log\Log::config() for more information on logging scopes.
  * @return bool Success

src/Log/LogTrait.php

@@ -13,6 +13,8 @@
  */
 namespace Cake\Log;
 
+use Psr\Log\LogLevel;
+
 /**
  * A trait providing an object short-cut method
  * to logging.
@@ -23,16 +25,13 @@ trait LogTrait {
  * Convenience method to write a message to Log. See Log::write()
  * for more information on writing to logs.
  *
- * @param string $msg Log message.
+ * @param mixed $msg Log message.
  * @param int|string $level Error level.
- * @param string|array $scope The name of the log scope.
+ * @param string|array $context Additional log data relevant to this message.
  * @return bool Success of log write.
  */
-	public function log($msg, $level = LOG_ERR, $scope = []) {
-		if (!is_string($msg)) {
-			$msg = print_r($msg, true);
-		}
-		return Log::write($level, $msg, $scope);
+	public function log($msg, $level = LogLevel::ERROR, $context = []) {
+		return Log::write($level, $msg, $context);
 	}
 
 }

tests/TestCase/Log/LogTraitTest.php

@@ -35,14 +35,14 @@ class LogTraitTest extends TestCase {
  * @return void
  */
 	public function testLog() {
-		$mock = $this->getMock('Cake\Log\LogInterface');
+		$mock = $this->getMock('Psr\Log\LoggerInterface');
 		$mock->expects($this->at(0))
 			->method('log')
 			->with('error', 'Testing');
 
 		$mock->expects($this->at(1))
 			->method('log')
-			->with('debug', print_r(array(1, 2), true));
+			->with('debug',array(1, 2));
 
 		Log::config('trait_test', ['engine' => $mock]);
 		$subject = $this->getObjectForTrait('Cake\Log\LogTrait');