Kotlin Code Smell 12 - Ripple Effect

TL;DR: If small changes have a significant impact, you need to decouple your system.

Problems

Coupling

Solutions

Decouple.
Cover with tests.
Refactor and isolate what is changing.
Depend on interfaces.

Examples

Legacy Systems

Sample Code

Wrong

class Time(
    private val hour: Int,
    private val minute: Int,
    private val seconds: Int
) {
    fun now() {
        // call operating system  
    } 
}

// Adding a TimeZone will have a big Ripple Effect
// Changing now() to consider timezone will also bring the effect

Right

// Removed now() since it is invalid without context
data class Time(
    private val hour: Int,
    private val minute: Int,
    private val seconds: Int,
    private val timezone: String
)

class RelativeClock(private val timezone: String) {
    fun now() {
        val localSystemTime = this.localSystemTime()
        val localSystemTimezone = this.localSystemTimezone()

        // Make some calculations to translate timezones...

        return Time(..., timezone)
    }

    // ...
}

Conclusion

There are multiple strategies to deal with legacy and coupled systems. It is essential to address this problem before it becomes unmanageable.

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