LogWriter

LogWriter takes care of deciding where to log the messages.

Prebuilt LogWriters

By default Kermit provides default LogWriter for each platform

• CommonWriter - Uses println to send logs in Kotlin
• LogcatWriter - Uses LogCat to send logs in Android
• OSLogWriter - Uses os log to send logs in iOS
• ConsoleWriter - Uses console to log in JS

These can be created and passed into the Logger object during initialization

Logger.setLogWriters(listOf(LogcatWriter(), CommonWriter()))

Selecting loggers for each platform can either be done with platform-specific entry points, or using an expect/actual factory function.

Kermit ships with a default factory function that provides a LogWriter suited to local development.

package co.touchlab.kermit

expect fun platformLogWriter(messageStringFormatter: MessageStringFormatter = DefaultFormatter): LogWriter

You can implement a factory function for your project similar to the one above.

Custom LogWriter

If you want to have a custom implementation to send logs to your own server, or a 3rd party tool or simply because default implementation doesn't fit your need, then you would need to extend the LogWriter class and provide your own instance.

For a simple LogWriter you only need to implement the log method, which handles all log messages.

Simple implementation would look like below,

class YourCustomWriter : LogWriter() {
    override fun log(severity: Severity, message: String, tag: String, throwable: Throwable?) {
        // Handle logging here
    }
}

Custom loggers may also override isLoggable. Kermit will check this value before logging to this LogWriter.

open fun isLoggable(tag: String, severity: Severity): Boolean = true

If your custom logger should only send messages in production, the implementation could look like the following:

// LogWriter
class YourCustomWriter(private val isProduction:Boolean) : LogWriter() {
    override fun log(severity: Severity, message: String, tag: String, throwable: Throwable?) {
        // Do something custom
    }

    override fun isLoggable(tag: String, severity: Severity): Boolean = isProduction
}

// Usage 
val logWriter = YourCustomWriter(someProdFlag)
val logger = Logger(loggerConfigInit(logWriter))