Rcpp: sourceCpp – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

sourceCpp

Source C++ Code from a File or String

Description

sourceCpp parses the specified C++ file or source code and looks for functions marked with the Rcpp::export attribute and RCPP_MODULE declarations. A shared library is then built and its exported functions and Rcpp modules are made available in the specified environment.

Usage

sourceCpp(file = "", code = NULL, env = globalenv(), embeddedR = TRUE, rebuild = FALSE, 
          cacheDir = getOption("rcpp.cache.dir", tempdir()), cleanupCacheDir = FALSE,
          showOutput = verbose, verbose = getOption("verbose"), dryRun = FALSE,
          windowsDebugDLL = FALSE)

Arguments

`file`	A character string giving the path name of a file
`code`	A character string with source code. If supplied, the code is taken from this string instead of a file.
`env`	Environment where the R functions and modules should be made available.
`embeddedR`	`TRUE` to run embedded R code chunks.
`rebuild`	Force a rebuild of the shared library.
`cacheDir`	Directory to use for caching shared libraries. If the underlying file or code passed to `sourceCpp` has not changed since the last invocation then a cached version of the shared library is used. The default value of `tempdir()` results in the cache being valid only for the current R session. Pass an alternate directory to preserve the cache across R sessions.
`cleanupCacheDir`	Cleanup all files in the cacheDir that were not a result of this compilation. Note that this will cleanup the cache from all other calls to sourceCpp with the same cacheDir. This option should therefore only be specified by callers that provide a unique cacheDir per scope (e.g. chunk labels in a weaved document).
`showOutput`	`TRUE` to print `R CMD SHLIB` output to the console.
`verbose`	`TRUE` to print detailed information about generated code to the console.
`dryRun`	`TRUE` to do a dry run (showing commands that would be used rather than actually executing the commands).
`windowsDebugDLL`	`TRUE` to create a debug DLL on Windows (and ignored on other platforms).

Details

If the code parameter is provided then the file parameter is ignored.

Functions exported using sourceCpp must meet several conditions, including being defined in the global namespace and having return types that are compatible with Rcpp::wrap and parameter types that are compatible with Rcpp::as. See the Rcpp::export documentation for more details.

Content of Rcpp Modules will be automatically loaded into the specified environment using the Module and populate functions.

If the source file has compilation dependencies on other packages (e.g. Matrix, RcppArmadillo) then an Rcpp::depends attribute should be provided naming these dependencies.

It's possible to embed chunks of R code within a C++ source file by including the R code within a block comment with the prefix of /*** R. For example:

/*** R

# Call the fibonacci function defined in C++
fibonacci(10)

*/

Multiple R code chunks can be included in a C++ file. R code is sourced after the C++ compilation is completed so all functions and modules will be available to the R code.

Value

Returns (invisibly) a list with two elements:

`functions`	Names of exported functions
`modules`	Names of Rcpp modules

Note

The sourceCpp function will not rebuild the shared library if the source file has not changed since the last compilation.

The sourceCpp function is designed for compiling a standalone source file whose only dependencies are R packages. If you are compiling more than one source file or have external dependencies then you should create an R package rather than using sourceCpp. Note that the Rcpp::export attribute can also be used within packages via the compileAttributes function.

If you are sourcing a C++ file from within the src directory of a package then the package's LinkingTo dependencies, inst/include, and src directories are automatically included in the compilation.

If no Rcpp::export attributes or RCPP_MODULE declarations are found within the source file then a warning is printed to the console. You can disable this warning by setting the rcpp.warnNoExports option to FALSE.

Examples

## Not run: 

sourceCpp("fibonacci.cpp")

sourceCpp(code='
  #include <Rcpp.h>

  // [[Rcpp::export]]
  int fibonacci(const int x) {
    if (x == 0) return(0);
    if (x == 1) return(1);
    return (fibonacci(x - 1)) + fibonacci(x - 2);
  }'
)


## End(Not run)

Rcpp

Seamless R and C++ Integration

v1.0.6

GPL (>= 2)

Authors

Dirk Eddelbuettel, Romain Francois, JJ Allaire, Kevin Ushey, Qiang Kou, Nathan Russell, Douglas Bates and John Chambers

Initial release

2021-01-14