The following code is problematic:

// at file scope - global variable

const_val< long> MAX_USERS( get_prop( "max_users") );

AllUsers::AllUsers()

{

    // here, we cannot be sure that MAX_USERS has been initialized

    std::cout << "there are max " << MAX_USERS << " users that can login." << std::endl;

}

However, the following code is not problematic

AllUsers::AllUsers()

{

    // local variable

    const long MAX_USERS( get_prop( "max_users") );

    // here, MAX_USERS is initialized

    std::cout << "there are max " << MAX_USERS << " users that can login." << std::endl;

}