16.10 Custom Accessors
When accessing the accountBalance property in the previous section, the code is making use of property accessors that are provided automatically by Kotlin. In addition to these default accessors it is also possible to implement custom accessors that allow calculations or other logic to be performed before the property is returned or set.
Custom accessors are implemented by creating getter and optional corresponding setter methods containing the code to perform any tasks before returning the property. Consider, for example, that the BankAcccount class might need an additional property to contain the current balance less any recent banking fees. Rather than use a standard accessor, it makes more sense to use a custom accessor which calculates this value on request. The modified BankAccount class might now read as follows:
class BankAccount (val accountNumber: Int, var accountBalance: Double) {
val fees: Double = 25.00
...