Section 10.20 Pure Functions
A pure function does not produce side effects. It communicates with the calling program only through parameters (which it does not modify) and a return value. Here is the
doubleStuff function from the previous section written as a pure function. To use the pure function version of
double_stuff to modify
things, you would assign the return value back to
Once again, codelens helps us to see the actual references and objects as they are passed and returned.