Accessing private fields
In Dart, as discussed when we covered packages, the privacy is at the library level, but it is still possible to have private fields in a class even though Dart does not have the keywords public, protected, and private. A simple return of a private field's value can be performed with a one-line function:
String getFirstName() => _name;
To retrieve this value, a function call is required, for example, Person.getFirstName(); however, it may be preferable to have a property syntax such as Person.firstName. Having private fields and retaining the property syntax in this manner is possible using the get and set keywords.
Using true getters and setters
The syntax of Dart also supports get and set via keywords:
int get score => score + bonus; set score(int increase) => score += increase * level;
Using either get/set or simple fields is down to preference. It is perfectly possible to start with simple fields and scale up to getters and setters if more validation or processing is required.
The advantage of the get and set keywords in a library is that the intended interface for consumers of the package is very clear. Further, it clarifies which methods may change the state of the object and which merely report current values.