protected final <T> T __getAs(String name, Class<T> c) {
        Object o = __getRenderArg(name);
        if (null == o) return null;
        return (T) o;
    }
protected final < T > T __getAs ( String name , Class < T > c ) { Object o = __getRenderArg ( name ) ; if ( null == o ) return null ; return ( T ) o ; }
Get render arg and do type cast to the class specified

@param name
@param c
@param <T>
@return a render argument