Functions, methods, and associated functions

Functions, and by extension methods and associated functions, are a way to group functionality together in a way that allows for code reuse without having to re-write the code in each place that it is used.

The distinction between a function, method and associated function is as follows:

• A function is a grouping of code that is independent of any object
• A method is a function that is associated with an object and it uses self as the first parameter
• An associated function is a method but without the self parameter

Function Declaration

A function declaration consists of a few components

• The fn keyword
• A unique name for the function
• Comma separated optional parameters, and their types, inside ()
• An optional return type

Here is a template that applies to the aforementioned functions.

fn my_function(my_parameter: u64 /* ... */ ) -> u64 {
    // function code
    42
}