diff --git a/library/log4php/helpers/LoggerOptionConverter.php b/library/log4php/helpers/LoggerOptionConverter.php
new file mode 100644
--- /dev/null
+++ b/library/log4php/helpers/LoggerOptionConverter.php
@@ -0,0 +1,232 @@
+<?php
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @package log4php
+ */
+
+/**
+ * A convenience class to convert property values to specific types.
+ *
+ * @version $Revision: 1374617 $
+ * @package log4php
+ * @subpackage helpers
+ * @since 0.5
+ */
+class LoggerOptionConverter {
+
+    /** String values which are converted to boolean TRUE. */
+    private static $trueValues = array('1', 'true', 'yes', 'on');
+
+    /**
+     * String values which are converted to boolean FALSE.
+     *
+     * Note that an empty string must convert to false, because
+     * parse_ini_file() which is used for parsing configuration
+     * converts the value _false_ to an empty string.
+     */
+    private static $falseValues = array('0', 'false', 'no', 'off', '');
+
+    /**
+     * Read a predefined var.
+     *
+     * It returns a value referenced by <var>$key</var> using this search criteria:
+     * - if <var>$key</var> is a constant then return it. Else
+     * - if <var>$key</var> is set in <var>$_ENV</var> then return it. Else
+     * - return <var>$def</var>.
+     *
+     * @param string $key The key to search for.
+     * @param string $def The default value to return.
+     * @return string    the string value of the system property, or the default
+     *                    value if there is no property with that key.
+     */
+    public static function getSystemProperty($key, $def) {
+        if (defined($key)) {
+            return (string)constant($key);
+        } else if (isset($_SERVER[$key])) {
+            return (string)$_SERVER[$key];
+        } else if (isset($_ENV[$key])) {
+            return (string)$_ENV[$key];
+        } else {
+            return $def;
+        }
+    }
+
+    /** Converts $value to boolean, or throws an exception if not possible. */
+    public static function toBooleanEx($value) {
+        if (isset($value)) {
+            if (is_bool($value)) {
+                return $value;
+            }
+            $value = strtolower(trim($value));
+            if (in_array($value, self::$trueValues)) {
+                return true;
+            }
+            if (in_array($value, self::$falseValues)) {
+                return false;
+            }
+        }
+
+        throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to boolean.");
+    }
+
+    /**
+     * Converts $value to integer, or throws an exception if not possible.
+     * Floats cannot be converted to integer.
+     */
+    public static function toIntegerEx($value) {
+        if (is_integer($value)) {
+            return $value;
+        }
+        if (is_numeric($value) && ($value == (integer)$value)) {
+            return (integer)$value;
+        }
+
+        throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to integer.");
+    }
+
+    /**
+     * Converts $value to integer, or throws an exception if not possible.
+     * Floats cannot be converted to integer.
+     */
+    public static function toPositiveIntegerEx($value) {
+        if (is_integer($value) && $value > 0) {
+            return $value;
+        }
+        if (is_numeric($value) && ($value == (integer)$value) && $value > 0) {
+            return (integer)$value;
+        }
+
+        throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to a positive integer.");
+    }
+
+    /** Converts the value to a level. Throws an exception if not possible. */
+    public static function toLevelEx($value) {
+        if ($value instanceof LoggerLevel) {
+            return $value;
+        }
+        $level = LoggerLevel::toLevel($value);
+        if ($level === null) {
+            throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to a logger level.");
+        }
+        return $level;
+    }
+
+    /**
+     * Converts a value to a valid file size (integer).
+     *
+     * Supports 'KB', 'MB' and 'GB' suffixes, where KB = 1024 B etc.
+     *
+     * The final value will be rounded to the nearest integer.
+     *
+     * Examples:
+     * - '100' => 100
+     * - '100.12' => 100
+     * - '100KB' => 102400
+     * - '1.5MB' => 1572864
+     *
+     * @param mixed $value File size (optionally with suffix).
+     * @return integer Parsed file size.
+     */
+    public static function toFileSizeEx($value) {
+
+        if (empty($value)) {
+            throw new LoggerException("Empty value cannot be converted to a file size.");
+        }
+
+        if (is_numeric($value)) {
+            return (integer)$value;
+        }
+
+        if (!is_string($value)) {
+            throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to a file size.");
+        }
+
+        $str = strtoupper(trim($value));
+        $count = preg_match('/^([0-9.]+)(KB|MB|GB)?$/', $str, $matches);
+
+        if ($count > 0) {
+            $size = $matches[1];
+            $unit = $matches[2];
+
+            switch ($unit) {
+                case 'KB':
+                    $size *= pow(1024, 1);
+                    break;
+                case 'MB':
+                    $size *= pow(1024, 2);
+                    break;
+                case 'GB':
+                    $size *= pow(1024, 3);
+                    break;
+            }
+
+            return (integer)$size;
+        }
+
+        throw new LoggerException("Given value [$value] cannot be converted to a file size.");
+    }
+
+    /**
+     * Converts a value to string, or throws an exception if not possible.
+     *
+     * Objects can be converted to string if they implement the magic
+     * __toString() method.
+     *
+     */
+    public static function toStringEx($value) {
+        if (is_string($value)) {
+            return $value;
+        }
+        if (is_numeric($value)) {
+            return (string)$value;
+        }
+        if (is_object($value) && method_exists($value, '__toString')) {
+            return (string)$value;
+        }
+
+        throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to string.");
+    }
+
+    /**
+     * Performs value substitution for string options.
+     *
+     * An option can contain PHP constants delimited by '${' and '}'.
+     *
+     * E.g. for input string "some ${FOO} value", the method will attempt
+     * to substitute ${FOO} with the value of constant FOO if it exists.
+     *
+     * Therefore, if FOO is a constant, and it has value "bar", the resulting
+     * string will be "some bar value".
+     *
+     * If the constant is not defined, it will be replaced by an empty string,
+     * and the resulting string will be "some  value".
+     *
+     * @param string $string String on which to perform substitution.
+     * @return string
+     */
+    public static function substConstants($string) {
+        preg_match_all('/\${([^}]+)}/', $string, $matches);
+
+        foreach ($matches[1] as $key => $match) {
+            $match = trim($match);
+            $search = $matches[0][$key];
+            $replacement = defined($match) ? constant($match) : '';
+            $string = str_replace($search, $replacement, $string);
+        }
+        return $string;
+    }
+}