Overloading Functions and Procedures

Sometimes it is useful to be able to have different options for how a function or procedure can be called. For example, in SplashKit you can call refresh_screen(); or refresh_screen(60); where you pass in a frame rate to limit the program to. This looks like the same procedure, but is actually two different procedures with different parameters. Another example is to_string. This can take a double or an integer, and return you back its textual representation.

This language feature is called overloading. It allows you to create functions or procedures with the same name as long as they have different numbers or types of parameters. In our examples, refresh_screen had either 0 or 1 parameter, while to_string has different types of parameters (int, double, etc). In either case, the compiler uses the arguments to work out which function or procedure to call.

While you can differ on the number or type of parameters, languages don’t allow you to differ on the return type. So if you want to return different data, but have the same parameters, then you need a new name for the function.

Languages like C and Python do not support overloading. This means that you need to come up with unique names for all of your functions and procedures. This was one of the features that the C++ language added, which is why we have been able to use this so far. Most modern languages support this, but it is something to look our for as you start to work with other languages.

Note

Python does not support function overloading, but you can achieve many of the same effects in other ways with the language.