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Defining loggers

Klogging provides a number of ways of defining loggers.

Implement Klogging interface​

The interface io.klogging.Klogging includes a logger property that returns a Klogger instance with the name of the class. For example:

package com.example

import io.klogging.Klogging

class ImportantService : Klogging {

    suspend fun beImportant() {
        // This logger has the name "com.example.ImportantService".
        logger.info("Being important")
    }
}
note

The Klogging functions are all suspend functions to be called in coroutine contexts.

Similarly, for non-coroutine contexts, the NoCoLogging interface has a logger property that returns a NoCoLogger instance. NoCoLogger has the same functions as Klogger but they are not suspend functions.

note

The logger property is not static and its get() function is called every time it is referenced. You can define a logger directly if performance is important.

Define a logger directly​

The logger() function defines a logger directly by name, by class or by reified type. The following calls to logger are equivalent:

package com.example

import io.klogging.logger

class BusyService {
    val loggerByReifiedType = logger<BusyService>()
    val loggerByClass = logger(BusyService::class)
    val loggerByName = logger("com.example.BusyService")
}

All three loggerByReifiedType, loggerByClass and loggerByName refer to the same logger instance because they have the same name

Static reference​

For a single reference to a logger that is not looked up every time, define it in the companion object of a class:

import io.klogging.logger

class VeryBusyService {
    companion object {
        val logger = logger<VeryBusyService>()
    }
}