The Anatomy of a Log Request

knitr::opts_chunk$set(
    collapse = TRUE,
    comment = "#>"
)
library(logger)
## backup settings
oldconf <- list(
    threshold = log_threshold(),
    layout = log_layout(),
    formatter = log_formatter(),
    appender = log_appender())
## knitr not picking up stderr
log_appender(appender_stdout)
knitr::include_graphics("logger_structure.svg")

To make a successful log record, logger requires the below components:

Putting all these together (by explicitly setting the default config in the global namespace):

log_threshold(INFO)
log_formatter(formatter_glue)
log_layout(layout_simple)
log_appender(appender_console)
log_debug('I am a low level log message that will not be printed with a high log level threshold')
log_warn('I am a higher level log message that is very likely to be printed')

Note, that all logger definitions and requests are tied to a logging namespace, and one log request might trigger multiple logger definitions as well (stacking). Find more information on these in the Customizing the format and destination of log records vignette.

## restore settings
log_threshold(oldconf$threshold)
log_layout(oldconf$layout)
log_formatter(oldconf$formatter)
log_appender(oldconf$appender)


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logger documentation built on July 6, 2021, 5:07 p.m.