inst/doc/customize_logger.R

In logger: A Lightweight, Modern and Flexible Logging Utility

## ----pkgchecks, echo = FALSE--------------------------------------------------
## check if other logger packages are available and exit if not
for (pkg in c("devtools", "parallel")) {
  if (!requireNamespace(pkg, quietly = TRUE)) {
    warning(paste(pkg, "package not available, so cannot build this vignette"))
    knitr::knit_exit()
  }
}

## ----setup, include = FALSE---------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

library(logger)
log_appender(appender_stdout)

## -----------------------------------------------------------------------------
log_info("Hi, there!")
log_debug("How are you doing today?")
log_threshold()
log_threshold(TRACE)
log_debug("How are you doing today?")

## -----------------------------------------------------------------------------
log_level(INFO, "Hi, there!")

## -----------------------------------------------------------------------------
log_threshold(INFO)
log_debug("pst, can you hear me?")
log_info("no")

with_log_threshold(log_debug("pst, can you hear me?"), threshold = TRACE)
log_info("yes")

with_log_threshold(
  {
    log_debug("pst, can you hear me?")
    log_info("yes")
  },
  threshold = TRACE
)

## -----------------------------------------------------------------------------
FYI <- structure(450L, level = "FYI", class = c("loglevel", "integer"))
log_threshold(FYI)
log_debug("ping")
log_level(FYI, "ping")
log_info("pong")

## -----------------------------------------------------------------------------
log_threshold(INFO)
log_trace("Hi, there!", namespace = "kitchensink")
log_info("Hi, there!", namespace = "kitchensink")

## -----------------------------------------------------------------------------
log_threshold(TRACE, namespace = "kitchensink")
log_trace("Hi, there!", namespace = "kitchensink")
log_info("Hi, there!", namespace = "kitchensink")
log_trace("Hi, there!")

## -----------------------------------------------------------------------------
log_formatter(formatter_glue)
log_info("There are {nrow(mtcars)} cars in the mtcars dataset")
log_info("2 + 2 = {2+2}")

## -----------------------------------------------------------------------------
log_info(42)
log_info("The answer is {42}")
log_info("The answers are {1:5}")

## -----------------------------------------------------------------------------
log_layout(layout_json())
log_info(42)
log_info("The answer is {42}")
log_info("The answers are {1:5}")

## -----------------------------------------------------------------------------
logger <- layout_glue_generator(format = "{node}/{pid}/{namespace}/{fn} {time} {level}: {msg}")
log_layout(logger)

## -----------------------------------------------------------------------------
log_info("foo")

## -----------------------------------------------------------------------------
f <- function() log_info("foo")
f()

## -----------------------------------------------------------------------------
devtools::load_all(system.file("demo-packages/logger-tester-package", package = "logger"))
logger_tester_function(INFO, "hi from tester package")

## -----------------------------------------------------------------------------
log_threshold(namespace = "logger.tester")
log_threshold(WARN, namespace = "logger.tester")
logger_tester_function(INFO, "hi from tester package")
logger_tester_function(WARN, "hi from tester package")
log_info("I am still working in the global namespace")

## -----------------------------------------------------------------------------
log_layout()

## -----------------------------------------------------------------------------
## reset layout
log_layout(layout_simple)

## -----------------------------------------------------------------------------
log_appender()

## -----------------------------------------------------------------------------
t <- tempfile()
log_appender(appender_file(t))
log_info("where is this message going?")
log_appender()
readLines(t)
unlink(t)

## -----------------------------------------------------------------------------
## reset appender
log_appender(appender_stdout)

## -----------------------------------------------------------------------------
log_threshold()

## create a new logger with index 2
log_threshold(TRACE, index = 2)

## note that the original logger still have the same log level threshold
log_threshold()
log_threshold(index = 2)

## update the appender of the new logger
t <- tempfile()
log_appender(appender_file(t), index = 2)

## test both loggers
log_info("info msg")
log_debug("info msg")

readLines(t)
unlink(t)

## ----cleanup, include = FALSE-------------------------------------------------
logger:::namespaces_reset()