ioc__dependency_injection.kt

class Report(
    val women: List<Person>,
    val men: List<Person>
) {
    fun isEmpty(): Boolean {
        return women.isEmpty() && men.isEmpty()
    }
}

class ReportGenerator(
    private val repository: Repository,
    private val filter: (Report) -> Report
) {

    fun create(): Report {
        val people = repository.fetchAllPeople()

        val rawReport = splitByGender(people)
        if (rawReport.isEmpty()) {
            return rawReport
        }

        val filteredReport = filter(rawReport)
        return sortByName(filteredReport)
    }

    // ...
}

// Example:
val withPeopleOver21 = { report: Report ->
    val over21 = { person: Person -> person.age > 21 }
    Report(
        report.women.filter(over21),
        report.men.filter(over21)
    )
}

val generator = ReportGenerator(repository, withPeopleOver21)
val reportWithPeopleOver21 = generator.create()