private function _checkDeprecation($text) {
		if ($this->_isActive('checkDeprecation')) {
			$key = strtolower($text);
			if (array_key_exists($key, $this->_deprecatedFunctions)) {
				$msg = $this->_getMessage('DEPRECATED_FUNCTION', $this->_deprecatedFunctions[$key]['old'], $this->_deprecatedFunctions[$key]['version'], $this->_deprecatedFunctions[$key]['new']);
				$this->_writeError('checkDeprecation', $msg);
			}
		}
	}