A simple header-only logging library for C++.
Add 'LinkingTo: plogr' to 'DESCRIPTION', and '#include
Provides the header files for a stripped-down version of the plog header-only C++ logging library, and a method to log to R's standard error stream.
You can install
plogr from GitHub with:
LinkingTo: plogr to your
DESCRIPTION, and add
#include <plogr.h> to all modules where you want to access the logging. If your package has an univeral header file which you include from all modules, it's probably a good idea to insert the
#include directive there, so that all of your code has access to logging. The following system header files will be included:
time.h(on Linux/OS X)
The code shows a small usage example and a demo which we'll call from R below. (
Rcpp is not necessary to use
plogr, it is only needed to run the C++ code chunk.) The
init_r() function is the only new function added by the R package, and initializes a logger that logs to R's standard error stream. For further details consult the plog documentation; for compatibility reasons you won't find the file appenders in this package.
// [[Rcpp::depends(plogr)]]// [[Rcpp::export]]void// not necessary to use plogr
The R code below calls the
plogr_demo() C++ function defined above. Currently, the messages are printed straight to the standard error stream, so the message capturing mechanisms employed by
knitr don't work. We use a sink with a text connection to capture the messages, and print the contents of the variable to which the text connection assigns.
output <- character()con <- textConnection("output", "a")withr::with_message_sink(con, plogr_demo())close(con)cat(output, sep = "\n")#> [email protected]: test 2#> [email protected]: test 4#> [email protected]: test 5
Nothing is printed before we actually initialize the logger. Because it is initialized to the
info level, the debug log message is not shown, and only "test 2" comes through. After changing the log level, the debug message is also shown.
plog::init_r()to initialize logging via
REprintf(), allows changing the log level and passing the log level as string.