src/WorkerF/IOCContainer.php
public static function register($abstract, $concrete = NULL)
    {
        if ($concrete == NULL) {
            $instance = self::getInstance($abstract);
            self::singleton($instance);
        } else {
            $instance = self::getInstance($concrete);
            self::singleton($instance, $abstract);
        }
    }
public static function register($abstract, $concrete = NULL)
    {
        if ($concrete == NULL) {
            $instance = self::getInstance($abstract);
            self::singleton($instance);
        } else {
            $instance = self::getInstance($concrete);
            self::singleton($instance, $abstract);
        }
    }
register class, instantiate class, set instance to singleton.

@param  string $abstract abstract class name
@param  string $concrete concrete class name, if NULL, use abstract class name
@return void