logcat

A tiny Kotlin API for cheap logging on top of Android's normal Log class.

The logcat function has 3 parameters: an optional priority, an optional tag, and a required string producing lambda (message). The lambda is only evaluated if a logger is installed and the logger deems the priority loggable.

The priority defaults to LogPriority.DEBUG.

The tag defaults to the class name of the log call site, without any extra runtime cost. This works because logcat is an inlined extension function of Any and has access to this from which it can extract the class name. If logging from a standalone function which has no this, use the logcat overload which requires a tag parameter.

The logcat function does not take a Throwable parameter. Instead, the library provides a Throwable extension function: Throwable.asLog which returns a loggable string.

import logcat.LogPriority.INFO
import logcat.asLog
import logcat.logcat

class MouseController {

  fun play {
    var state = "CHEEZBURGER"
    logcat { "I CAN HAZ $state?" }
    // logcat output: D/MouseController: I CAN HAZ CHEEZBURGER?

    logcat(INFO) { "DID U ASK 4 MOAR INFO?" }
    // logcat output: I/MouseController: DID U ASK 4 MOAR INFO?

    logcat { exception.asLog() }
    // logcat output: D/MouseController: java.lang.RuntimeException: FYLEZ KERUPTED
    //                        at sample.MouseController.play(MouseController.kt:22)
    //                        ...

    logcat("Lolcat") { "OH HI" }
    // logcat output: D/Lolcat: OH HI
  }
}

To install a logger, see LogcatLogger.

An overload for logging that does not capture the calling code as tag. This should only be used in standalone functions where there is no this.

See also