Methods

Say you have a block of code that you want to execute more than once. For example, let’s look at our previous spoonSize program. Suppose you have a set of several spoons and want to check all of their sizes. Instead of writing out those five lines of code over and over again, you can delegate it to a method.

Here is an example of a method declaration:

method checkSpoonSize(spoonSize) {
    if (spoonSize < 20) then {
        print "My spoon is too small!"
    } else {
        print "My spoon is too big!"
    }
}

The reserved word method says that we are staring a method declaration. Then comes the name of the method, and (optionally) a list of parameters.

Now that we have declared a method, we can request it. Requesting that Grace execute this method is as simple as writing checkSpoonSize(15). We write the name of the method and give it the appropriate arguments, in our case, 15. When the method executes, the parameter spoonSize takes on the value of the argument, that is, 15.

Multi-part method names

There are a variety of formats for method names and parameter lists. You can have multiple parameters, as in the method multiply(a, b) below. The name of the method can also have multiple parts, each with its own list of parameters, as illustrated by divide(a) by(b) below. Lastly, you can also have a name with no parameters, shown by pi below.

One form that is not allowed is a multipart name without a parameter list after the final part. So `method divide (a, b) by` is not allowed.

A word on terminology

The variables names in parenthesis in the method header, like spoonSize in the method checkSpoonSize are called parameters. When you make a request of such a method, you provide values for those parameters by supplying arguments, like 5 or 15. So the parameter is a name, while the argument is a value, or an expression that can be evaluated to yield a value.