15. Functions

Functions are a way to save time and energy by storing commonly used blocks of code in one named set. For a real-world example, when you’re drinking a glass of water, the entire task might look like this:

1. Find glass
2. Bring over to water source
3. Pour water into glass
4. Make sure water doesn’t overflow!
5. Drink water

But instead of saying all of that, you could just say you’re drinking water! Functions work the same way. Multiple lines of code can be included in one function that you name and set up to be used in your program.

To define a function, or explain what is going to be in it, you will need the ‘to do something’ block in the pink functions menu. Drag that to your workspace and then name your function in the white box. This should be something memorable that describes your function well. Next, drag the blocks you need into the function.

Try it now! Make a function that has the name “blink” that has Zumi go forward and then blink.

Once you define a function, you should see a block for it in the functions menu. To use it, drag it into your workspace and drop it to wherever you would like to see it in your program.

What if we want the function to do something different depending on the parameters we provide? Remember that you can change the number of seconds Zumi drives forward. You can also add parameters to your functions! In order to add parameters to your function in Blockly, click on the gear icon and attach an input block to the inputs block. The input can then be accessed from the variables tab.

Warning: If you plan on using your function later on, do not remove it from your workspace! Doing this will delete the entire function nd you will not be able to locate it in the functions menu.

Write a function that makes Zumi drive in a rectangle pattern using two parameters (one of the long sides and one for the short sides). Try using the function with different parameter values and see what kinds of rectangles you can come up with!

Once you’ve made your rectangle function, try comparing it to either of the solutions below! Remember, when you want to call a custom function make sure that you drag the function block onto your workspace after defining the function.

The first solution makes Zumi drive in a rectangle shape using right turns:

The second solution makes Zumi drive in a rectangle shape using left turns instead of right turns:

In this lesson, you learned how to use the function blocks to define functions and call them in your program! The function block is helpful for when you have commonly-used code that repeats often, and can be used to make your code smaller and more efficient.