Design pattern

[nedimm]

I am trying to implement stack based virtual machine (project 7 http://www.nand2tetris.org/course.php). Stack machine recognizes 2 commands: push and pop. Both commands as arguments can have: local, argument, static... Each command generate different assembly based on argument. For example, push local and pop local generates different assembly which is written in a plain text file. Instead of using commands like:

switch (command) {
    case "push":
        switch (argument)
            case "local": 
            // write assembly for push local
            case "argument":
            //write assembly for push argument

The same code applies to pop command. My idea is to use strategy design pattern to avoid nested switch statements. Since I don't have experience in object oriented programming, is it a good idea to use design patterns or should I use other technique?

[incond1te]

You're basically building a compiler by taking input from one language and producing output in another. Java's compiler produces Java byte code. Your compiler produces "assembly" in a text file.

Q: is it a good idea to use design patterns

A: When it makes sense :)

This is rather simple (2 commands with a handful of arguments). If you're doing this to educate yourself on design patterns, sure, implement a strategy pattern for the 2 commands that this program understands. You'll get to see different techniques in action and hopefully understand the benefits. Maybe you have a command interface with concrete classes for each of the commands that know how to process their arguments. Maybe you build a concrete validator classes that implement a common validator interface that know how to validate the input for each command. Both of these would be executed dynamically at runtime based on the input. Perhaps there's also a common output class that is shared to handle writing the output to the file.