inst/doc/anatomy.R

In logger: A Lightweight, Modern and Flexible Logging Utility

## ----setup, include = FALSE---------------------------------------------------
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)

## ----loggerStructureImage, echo=FALSE, out.extra='style="width: 100%;" title="The structure of a logger and the flow of a log record request" alt="The structure of a logger and the flow of a log record request"'----
knitr::include_graphics("logger_structure.svg")

## -----------------------------------------------------------------------------
f <- function() get_logger_meta_variables(log_level = INFO)
f()

## -----------------------------------------------------------------------------
log_threshold()
ERROR <= INFO
log_error('Oops')

## -----------------------------------------------------------------------------
formatter <- function(...) paste(..., collapse = ' ', sep = ' ')
formatter(1:3, c('foo', 'bar'))

## -----------------------------------------------------------------------------
appender <- function(line) cat(line, '\n')
appender('INFO [now] I am a log message')

## -----------------------------------------------------------------------------
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')

## ----cleanup, include = FALSE-------------------------------------------------
## restore settings
log_threshold(oldconf$threshold)
log_layout(oldconf$layout)
log_formatter(oldconf$formatter)
log_appender(oldconf$appender)