plogr [![Travis-CI Build Status](https://travis-ci.org/krlmlr/plogr.svg?branch=master)](https://travis-ci.org/krlmlr/plogr) [![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/github/krlmlr/plogr?branch=master&svg=true)](https://ci.appveyor.com/project/krlmlr/plogr) ============================================================================================================================================================================================================================================================================================ Provides the header files for a stripped-down version of the [plog](https://github.com/SergiusTheBest/plog) header-only C++ logging library, and a method to log to R's standard error stream. Installation ------------ You can install `plogr` from GitHub with: ``` r # install.packages("devtools") devtools::install_github("krlmlr/plogr") ``` Usage ----- Add `LinkingTo: plogr` to your `DESCRIPTION`, and add `#include ` to all modules where you want to access the logging. If your package has a universal 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: - `sstream` - `iostream` - `vector` - `cassert` - `cstring` - `time.h` (on Linux/OS X) - `sys/time.h` (on Windows) - `R.h` Example ------- 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](https://github.com/SergiusTheBest/plog#readme); for compatibility reasons you won't find the file appenders in this package. ``` cpp // If we omit this, logging is disabled altogether. // In a package, you would probably add -DPLOGR_ENABLE to PKG_CPPFLAGS. #define PLOGR_ENABLE // [[Rcpp::depends(plogr)]] #include // [[Rcpp::export]] void plogr_demo() { LOG_INFO << "test 1"; plog::init_r(plog::info); LOG_INFO << "test 2"; LOG_DEBUG << "test 3"; plog::init_r("DEBUG"); // You can also pass a string LOG_INFO << "test 4"; LOG_DEBUG << "test 5"; } #include // 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. ``` r output <- character() con <- textConnection("output", "a") withr::with_message_sink(con, plogr_demo()) close(con) cat(output, sep = "\n") #> void plogr_demo@12: test 2 #> void plogr_demo@15: test 4 #> void plogr_demo@16: 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.

plogr0.2.0 package

Functions

Readme

Versions

News

plogr-package