From callr version 2.0.0, r() is equivalent to r_safe(), and
tries to set up a less error prone execution environment. In particular:
Ensures that at least one reasonable CRAN mirror is set up.
Adds some command line arguments to avoid saving .RData files, etc.
Ignores the system and user profiles (by default).
Sets various environment variables: CYGWIN to avoid
warnings about DOS-style paths, R_TESTS to avoid issues
when callr is invoked from unit tests, R_BROWSER
and R_PDFVIEWER to avoid starting a browser or a PDF viewer.
See rcmd_safe_env().
r(
func,
args = list(),
libpath = .libPaths(),
repos = default_repos(),
stdout = NULL,
stderr = NULL,
poll_connection = TRUE,
error = getOption("callr.error", "error"),
cmdargs = c("--slave", "--no-save", "--no-restore"),
show = FALSE,
callback = NULL,
block_callback = NULL,
spinner = show && interactive(),
system_profile = FALSE,
user_profile = "project",
env = rcmd_safe_env(),
timeout = Inf,
package = FALSE,
arch = "same",
...
)r_safe(
func,
args = list(),
libpath = .libPaths(),
repos = default_repos(),
stdout = NULL,
stderr = NULL,
poll_connection = TRUE,
error = getOption("callr.error", "error"),
cmdargs = c("--slave", "--no-save", "--no-restore"),
show = FALSE,
callback = NULL,
block_callback = NULL,
spinner = show && interactive(),
system_profile = FALSE,
user_profile = "project",
env = rcmd_safe_env(),
timeout = Inf,
package = FALSE,
arch = "same",
...
)
Value of the evaluated expression.
Function object to call in the new R process.
The function should be self-contained and only refer to
other functions and use variables explicitly from other packages
using the :: notation. By default the environment of the function
is set to .GlobalEnv before passing it to the child process.
(See the package option if you want to keep the environment.)
Because of this, it is good practice to create an anonymous
function and pass that to callr, instead of passing
a function object from a (base or other) package. In particular
r(.libPaths)
does not work, because .libPaths is defined in a special
environment, but
r(function() .libPaths())
works just fine.
Arguments to pass to the function. Must be a list.
The library path.
The repos option. If NULL, then no
repos option is set. This options is only used if
user_profile or system_profile is set FALSE,
as it is set using the system or the user profile.
The name of the file the standard output of
the child R process will be written to.
If the child process runs with the --slave option (the default),
then the commands are not echoed and will not be shown
in the standard output. Also note that you need to call print()
explicitly to show the output of the command(s).
IF NULL (the default), then standard output is not returned, but
it is recorded and included in the error object if an error happens.
The name of the file the standard error of
the child R process will be written to.
In particular message() sends output to the standard
error. If nothing was sent to the standard error, then this file
will be empty. This argument can be the same file as stdout,
in which case they will be correctly interleaved. If this is the
string "2>&1", then standard error is redirected to standard output.
IF NULL (the default), then standard output is not returned, but
it is recorded and included in the error object if an error happens.
Whether to have a control connection to the process. This is used to transmit messages from the subprocess to the main process.
What to do if the remote process throws an error. See details below.
Command line arguments to pass to the R process.
Note that c("-f", rscript) is appended to this, rscript
is the name of the script file to run. This contains a call to the
supplied function and some error handling code.
Logical, whether to show the standard output on the screen
while the child process is running. Note that this is independent
of the stdout and stderr arguments. The standard
error is not shown currently.
A function to call for each line of the standard
output and standard error from the child process. It works together
with the show option; i.e. if show = TRUE, and a
callback is provided, then the output is shown of the screen, and the
callback is also called.
A function to call for each block of the standard output and standard error. This callback is not line oriented, i.e. multiple lines or half a line can be passed to the callback.
Whether to show a calming spinner on the screen while
the child R session is running. By default it is shown if
show = TRUE and the R session is interactive.
Whether to use the system profile file.
Whether to use the user's profile file.
If this is "project", then only the profile from the working
directory is used, but the R_PROFILE_USER environment variable
and the user level profile are not. See also "Security considerations"
below.
Environment variables to set for the child process.
Timeout for the function call to finish. It can be a
base::difftime object, or a real number, meaning seconds.
If the process does not finish before the timeout period expires,
then a system_command_timeout_error error is thrown. Inf
means no timeout.
Whether to keep the environment of func when passing
it to the other package. Possible values are:
FALSE: reset the environment to .GlobalEnv. This is the default.
TRUE: keep the environment as is.
pkg: set the environment to the pkg package namespace.
Architecture to use in the child process, for multi-arch
builds of R. By default the same as the main process. See
supported_archs(). If it contains a forward or backward slash
character, then it is taken as the path to the R executable.
Note that on Windows you need the path to Rterm.exe.
Extra arguments are passed to processx::run().
callr handles errors properly. If the child process throws an
error, then callr throws an error with the same error message
in the main process.
The error expert argument may be used to specify a different
behavior on error. The following values are possible:
error is the default behavior: throw an error in the main process,
with a prefix and the same error message as in the subprocess.
stack also throws an error in the main process, but the error
is of a special kind, class callr_error, and it contains
both the original error object, and the call stack of the child,
as written out by utils::dump.frames(). This is now deprecated,
because the error thrown for "error" has the same information.
debugger is similar to stack, but in addition
to returning the complete call stack, it also start up a debugger
in the child call stack, via utils::debugger().
The default error behavior can be also set using the callr.error
option. This is useful to debug code that uses callr.
callr uses parent errors, to keep the stacks of the main process and the subprocess(es) in the same error object.
callr makes a copy of the user's .Renviron file and potentially of
the local or user .Rprofile, in the session temporary
directory. Avoid storing sensitive information such as passwords, in
your environment file or your profile, otherwise this information will
get scattered in various files, at least temporarily, until the
subprocess finishes. You can use the keyring package to avoid passwords
in plain files.
func and args are copied to the child process by first serializing them
into a temporary file using saveRDS() and then loading them back into the
child session using readRDS(). The same strategy is used to copy the result
of calling func(args) to the main session. Note that some objects, notably
those with externalptr type, won't work as expected after being
saved to a file and loaded back.
For performance reasons compress=FALSE is used when serializing with
saveRDS(), this can be disabled by setting
options(callr.compress_transport = TRUE).
The r() function from before 2.0.0 is called r_copycat() now.
Other callr functions:
r_copycat(),
r_vanilla()
if (FALSE) {
# Workspace is empty
r(function() ls())
# library path is the same by default
r(function() .libPaths())
.libPaths()
}
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