Question

I’m dealing with a program that does plenty of if…else branching based on command line arguments. This is in C# but I’m sure it’s applicable to Java, C++ etc. Here’s the general outline:

if (args.Length == 0)
{
  //do something
}

if (args.Length > 0 && args.Length < 2)
    {
        Console.WriteLine("Only one argument specified. Need two arguments");
        return 0;

    }
            else if (args.Length > 0 && args.Length >= 2)
            {
                //Process file - Argument 1
                if(args[0].Trim() == PROCESS_OPTION_ONE
                    || args[0].Trim() == PROCESS_OPTION_TWO)
                {
                    //Process file - Argument 2
                    if(args[1].Trim() == PROCESS_CUSTOMER
                        || args[1].Trim() == PROCESS_ADMIN
                        || args[1].Trim() == PROCESS_MEMBER
                        || args[1].Trim() == PROCESS_GUEST
                        || args[1].Trim() == PROCESS_USER
                        )
                    {

So as you can tell, it’s kind of a mess. Is there a design pattern or two that would be most applicable toward cleaning things up some? Command pattern, perhaps? Thanks for the advice and tips.

Answer 1

I’m partial to using switch statements on the arguments array and setting properties in a configuration class of some kind for each anticipated argument. It appears you’re expecting a very specifically formatted argument string rather than allowing set values, you could try:

if(args[0].Trim() == PROCESS_OPTION_ONE || args[0].Trim() == PROCESS_OPTION_TWO) 
{ 
    //Process file - Argument 2
    switch(args[1].Trim()
    {
        case PROCESS_CUSTOMER, PROCESS_ADMIN, PROCESS_MEMBER, PROCESS_GUEST, PROCESS_USER:
            // Do stuff
            break;
        default:
            // Do other stuff
            break;
    }
}

My preferred method would be something like

foreach(string arg in args)
{
    switch(arg)
    {
        case PROCESS_CUSTOMER:
            // Set property
            break;
        ...
        default:
            // Exception?
            break;
    }
}

NOTE: args.Length == 1 is faster than args.Length > 0 && args.Length < 2. It’s also a little more readable.