W4MRUtils (version 1.0.0)

get_logger: Instantiate a Logger

Description

Create a logger of the given name. You can call again get_logger and provide the same name to get the same logger. It will not be recreated unless recreate is TRUE.

Usage

get_logger(name, recreate = FALSE, ...)

Value

A new W4MLogger instance if it did not exist or if recreate is TRUE. Otherwise, a new W4MLogger instance.

Arguments

name

the name of the logger to get or create. This name will be used in logs to differentiate from which part of you program comes which lines of log. See the example of usage bellow.

recreate

logical=FALSE tells whether to recreate the logger of the given name or not. Preferably, one should not recreate a new logger each time.

...

Arguments passed on to W4MLogger

Author

L.Pavot

Details

get_logger

Examples

## let's say our program is divided in three big tasks:
##   - the parsing
##   - the processing
##   - the output writing
parser_logger <- W4MRUtils::get_logger("Parser")
process_logger <- W4MRUtils::get_logger("Processing")
write_logger <- W4MRUtils::get_logger("Writer")
input_path <- "/home/anyone/input.csv"
parser_logger$info(paste("Parsing the input file at", input_path))
parser_logger$debug("Input extension detected: csv")
parser_logger$debug("The csv parser program will be used")
## do the parsing...
input <- list(a=1:5, b=5:10, c=8:2)
parser_logger$info("Parsing succeed")
process_logger$info("Starting the processing of:", input)
process_logger$debug("The processing has started at...")
result <- as.list(input)
process_logger$debug("The processing has finished at...")
process_logger$info("Processing finished in x seconds.")
outfile <- "/home/anyone/output.tsv"
write_logger$info(paste("Creating the output in", outfile))

## we detected that the input was csv and the out was tsv:
## but it is not a blocking problem
write_logger$warning("The input and output file's extensions are different")
write_logger$debug("The output will be casted from csv to tsv")

## we try to write the file, but it fails
tryCatch({
  ## writing the output file failed with this error:
  stop(sprintf("I/O Error: %s is not writable.", outfile))
}, error = function(e) {
  write_logger$error(e$message)
  write_logger$error("Writing output file aborted.")
  ## quit(save = "no", status = 42)
})

## note that debug output were not written. To show debug logs
## we have to active it (disabled by default):

write_logger$set_debug()
write_logger$debug("The debug outputs are now visible!")