Logging from R Packages

In this vignette I suppose that you are already familiar with Customizing the format and destination of log records vignette, especially with the Log namespaces section.

So that your R package’s users can suppress (or render with custom layout) the log messages triggered by your R package, it’s wise to record all those log messages in a custom namespace. By default, if you are calling the ?log_level function family from an R package after importing from the logger package, then logger will try to auto-guess the calling R package name and use that as the default namespace, see eg:

#> Attaching package: 'logger'
#> The following object is masked from 'package:log4r':
#>     logger
devtools::load_all(system.file('demo-packages/logger-tester-package', package = 'logger'))
#> Loading logger.tester
logger_tester_function(INFO, 'hi from tester package')

But if auto-guessing is not your style, then feel free to set your custom namespace (eg the name of your package) in all ?log_info etc function calls and let your users know about how to suppress / reformat / redirect your log messages via ?log_threshold, ?log_layout, ?log_appender.

Please note that setting the formatter function via ?log_formatter should not be left to the R package end-users, as the log message formatter is specific to your logging calls, so that should be decided by the R package author. Feel free to pick any formatter function (eg glue, sprintf, paste or something else), and set that via ?log_formatter when your R package is loaded. All other parameters of your logger will inherit from the global namespace – set by your R package’s end user.