//performance tuning...
class WeatherService{
 
	private $cache;
 
	public function WeatherService(){
		//some initialization...
		$cache = new MemCache();
	}
 
	public function getWeatherInfo($city, $method){
 
		if ($cache->get()[$city])
			return $cache->get($city);
 
		$res = shell_exec("./getWdr.sh {$city}");
 
		$this->cache->set($city,$res);
 
		if ($methos=="CL")
			return convertFrToC($res);
 
		return $res;
	}
 
	private function convertFrToC($val){
		return (($val+40)*5/9)-40;
	}
 
}
 
 
class MemCache{
 
	private $mem;
 
	public function MemCache(){
		//some intitialization here...
		$mem = array();
	}
 
	public function get(){
		return $this->mem;
	}
 
	public function set($key, $val){
		echo "putting [$val] in $key";
		$this->mem[$key] = $val;
	}
}