logger (version 0.4.0)

logger: Generate logging utility

Description

A logger consists of a log level threshold, a log message formatter function, a log record layout formatting function and the appender function deciding on the destination of the log record. For more details, see the package README.md.

Usage

logger(threshold, formatter, layout, appender)

Value

A function taking the log level to compare with the set threshold, all the ... arguments passed to the formatter function, besides the standard namespace, .logcall, .topcall and .topenv arguments (see log_level() for more details). The function invisibly returns a list including the original level, namespace, all ... transformed to a list as params, the log message (after calling the formatter

function) and the log record (after calling the layout

function), and a list of handlers with the formatter, layout and appender functions.

Arguments

threshold

omit log messages below this log_levels()

formatter

function pre-processing the message of the log record when it's not wrapped in a skip_formatter() call

layout

function rendering the layout of the actual log record

appender

function writing the log record

Details

By default, a general logger definition is created when loading the logger package, that uses

• INFO() (or as per the LOGGER_LOG_LEVEL environment variable override) as the log level threshold

• layout_simple() as the layout function showing the log level, timestamp and log message

• formatter_glue() (or formatter_sprintf() if glue is not installed) as the default formatter function transforming the R objects to be logged to a character vector

• appender_console() as the default log record destination

References

For more details, see the Anatomy of a Log Request vignette at https://daroczig.github.io/logger/articles/anatomy.html.

Examples

if (FALSE) {
do.call(logger, logger:::namespaces$global[[1]])(INFO, 42)
do.call(logger, logger:::namespaces$global[[1]])(INFO, "{pi}")
x <- 42
do.call(logger, logger:::namespaces$global[[1]])(INFO, "{x}^2 = {x^2}")
}