Advanced

Working with custom frontends

Canard is a facade for multiplatform developers that need an easy way to log without worrying about platform specific implementation. For that we provide [default frontends] that are default output capacities, for each possible target of Kotlin/Multiplatform.

However, we can think of a lot of use cases that might not covered by default frontends, ike saving the logs into a file, sending the logs to an upstream system, etc.

If you want to use a custom implementation to handle your logs, you can create your own by using the interface LogFrontend.

logFrontend

public fun interface LogFrontend {
    public fun getReceiverFor(tag: Logger.Tag): LogReceiver (1)
}

1	You only have to override `getReceiverFor`.

The getReceiverFor function will define what we should do of every logged entry. The rest depends on your use case. Here is an example of a frontend that will stack every log into a list:

custom frontend

class MemoryFrontend : LogFrontend { (1)
    val entries: MutableList<Triple<Logger.Tag, Logger.Entry, String?>> = ArrayList() (2)

    override fun getReceiverFor(tag: Logger.Tag): LogReceiver = (3)
        LogReceiver { entry, message -> (4)
            entries += Triple(tag, entry, message) (5)
        }
}

1	implement `LogFrontend`
2	create a mutable list that will carry the logs
3	override `getReceiveFor`
4	create a `LogReceiver` …
5	… that populate the `entries` with each log received

We could use this example to periodically send our stack to an upstream server.