GoTo Command Versus GoSub Command (AutoHotkey Tip)

While the Online Documentation Advises Avoiding the AutoHotkey GoTo Command in Deference to GoSub or a User-Defined Function, You’ll Find Times When GoTo Works Best!

Not everyone likes their cheeseburger prepared the same way. Some prefer fried onions while others love the crunch of raw condiments. In fact, In-N-Out Burger touts a not-so-secret menu offering cheeseburgers “Animal Style.” The preparation of this option with caramelized onions and mustard fried hamburger significantly changes the cheeseburger experience. That gives us an excuse to add flexibility to our CheeseburgerRecipe.ahk script—first discussed in the blogs “Why AutoHotkey for Chefs and Dieticians?” and “Understanding Label Names and Subroutines (Beginning AutoHotkey Tip).”

Note: I changed the CheeseburgerRecipe.ahk script in a number of ways—a few of which I plan to discuss in future AutoHotkey Tips. For now, I confine myself to highlighting the use of the GoTo command. For specific changes, see the comments at the top of the CheeseburgerRecipe.ahk script.

Adding Options to the Cheeseburger Recipe

I found another recipe at FoodNetwork.com which replicates the In-N-Out Animal-Style Cheeseburger recipe. Copying the same AutoHotkey techniques I used for the Jack Stuffed Cheeseburger, I added the new steps for this recipe to the script. Since the System Tray menu grew too crowded, I implemented submenus for each recipe. (See image below.)

The primary differences between the Jack Stuffed Cheeseburger and the Animal-Style Cheeseburger include caramelizing onions, mixing a special sauce, burgers with no embedded cheese, preparation of the buns, and frying the burgers with mustard. While more involved than the first recipe, the new recipe might satisfy the “Animal” in anyone. But, what if you wanted a Jack Stuffed Cheeseburger Animal Style?

You could write an entirely new recipe for a Jack Stuffed Cheeseburger Animal Style but that would include a great deal of redundancy. By using the AutoHotkey GoTo command, we combine the redundant steps of the two recipes to create a third variation.

CheeseburgerGoTo — Each column represents one recipe subroutine followed by a single *Return* command at the end. Each box contains the *Label* name for the location of that individual step within the recipe. After each step, AutoHotkey automatically drops into the *Label* below since no *Return* command intervenes until the end of the recipe. The *GoTo* commands in the third recipe jump to the *Label* name point (e.g. *GoTo, Animal_Onions*) in the appropriate recipe subroutine—proceeding as if a totally separate recipe.

For the new Jack Stuffed Animal Style Cheeseburger, the recipe starts at the Label point Stuffed_Animal_Ingredients: which includes the ingredients for the Animal Style Cheeseburger plus the added Jack cheese (for stuffing) and varied meat and cheese amounts. Using the GoTo command, AutoHotkey jumps directly to the Animal_Onions: pointer for caramelizing the onions.

Since the process jumps into the middle of the Animal Style Cheeseburger subroutine, when the Animal Style Cheeseburger – Onions window closes, it automatically drops into the Animal_Sauce: routine. Next, the recipe must GoTo the Jack Stuffed Cheeseburger Label named Prepare: for shaping the burgers with Monterey Jack cheese inside. In order to make this jump decision, AutoHotkey must identify the currently running recipe subroutine: either Animal Style Cheese Burger (no Goto) or Jack Stuffed Animal Style (GoTo).

The initial menu selection tells us which recipe track to follow. The menu name (A_ThisMenu) identifies the Jack Stuffed Animal Style recipe:

If (A_ThisMenu = "StuffedAnimal")
  StuffedAnimal = 1
Else
  StuffedAnimal = 0

Placing this condition into the MessageSetup: subroutine identifies the origin of any mixed-use menu steps. AutoHotkey determines the proper path by checking the value of the StuffedAnimal variable. For example, after the Animal_Sauce: window, the process uses the following check:

If (StuffedAnimal = 1)
  GoTo, Prepare

If running the Jack Stuffed Animal Style sequence (StuffedAnimal = 1), AutoHotkey jumps to the Prepare: point of the Jack Stuffed Cheeseburger routine. Otherwise, the Animal Style Cheeseburger continues dropping through its steps.

This same conditional format creates the jumps from Prepare: to the Animal_Buns: point and from Animal_Buns: to the Stuffed_Animal_Cook: point for the Jack Stuffed Animal Style steps. This process creates a new variation from older recipes without rewriting redundant steps. Often using the GoSub command (for Go Subroutine) works better, but in this situation, GoTo makes the routine act as if it’s one continuous series of steps.

GoTo Versus GoSub

To understand the difference between the GoTo command and the GoSub command, know that when a subroutine finishes, the GoSub command returns to the next line in the original calling routine, while the GoTo command does not. In most cases, since it returns to the same spot in the script, you’ll probably find the GoSub command (or a function) more appropriate. But if you know that you don’t want to return to that point, then feel free to use GoTo—but you better know where you plan to end up.

A common usage of GoSub runs the subroutine then returns to the next line after the calling line. For example, I moved the loading of the recipe variables for each step out of the auto-execute section of the script into separate Label subroutines, then replaced each with a single GoSub command. This made the script more readable by greatly reducing the length of the auto-execute section. In place of the code, I inserted the following GoSub command statements:

GoSub, StuffedCheeseburger 
GoSub, AnimalCheeseburger
GoSub, StuffedAnimalCheeseburger

However, using the GoSub command in the mixed recipe scenario for the Jack Stuffed Cheeseburger Animal Style would have caused more problems than it solved. For example, if the GoSub command appeared in place of GoTo, then each call would create a new return point. That means clicking the Cancel button would cause the script to jump to the last GoSub call rather than exiting the thread. In many cases, jumping back would cause unwanted effects (e.g. display an inappropriate step from another recipe). In fact, even running through the entire recipe without canceling would cause an untold number of displays of various steps. After encountering the last Return in the subroutine, the final Return jump executes more GoSub commands—each creating an additional Return point. The GoTo command keeps it clean, allowing an exit with any Return encountered in any recipe sequence. To the user, each recipe (including the mixed) looks like a continuous set of steps.

While probably best avoided if GoSub or a function can do the job, the GoTo command works well in scripts emulating flow charts and plays an important role in decision trees. In those special situations, knowing where you are (and where you’re going) may be more important than where you’ve been.