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:
It makes sure that at least one reasonable CRAN mirror is set up.
Adds some command line arguments are added to avoid saving
.RData
files, etc.
Ignores the system and user profiles.
Various environment variables are set: 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 = c(getOption("repos"), c(CRAN = "https://cloud.r-project.org")),
stdout = NULL, stderr = NULL, error = getOption("callr.error", "error"),
cmdargs = c("--no-site-file", "--no-environ", "--slave", "--no-save",
"--no-restore"), show = FALSE, callback = NULL, block_callback = NULL,
spinner = show && interactive(), system_profile = FALSE,
user_profile = FALSE, env = rcmd_safe_env(), timeout = Inf)r_safe(func, args = list(), libpath = .libPaths(),
repos = c(getOption("repos"), c(CRAN = "https://cloud.r-project.org")),
stdout = NULL, stderr = NULL, error = getOption("callr.error", "error"),
cmdargs = c("--no-site-file", "--no-environ", "--slave", "--no-save",
"--no-restore"), show = FALSE, callback = NULL, block_callback = NULL,
spinner = show && interactive(), system_profile = FALSE,
user_profile = FALSE, env = rcmd_safe_env(), timeout = Inf)
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. The environment of the function
is set to .GlobalEnv
before passing it to the child process.
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).
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 can be the same file as stderr
, although there
is no guarantee that the lines will be in the correct chronological
order.
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.
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.
Value of the evaluated expression.
callr
handles errors properly. If the child process throws an
error, then callr
throws an error with the same error message
in the parent 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 parent, with
the same error message. In fact the same error object is thrown again.
stack
also throws an error in the parent, 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()
.
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
.
The pre-2.0.0 r()
function is called r_copycat()
now.
# NOT RUN {
# Workspace is empty
r(function() ls())
# library path is the same by default
r(function() .libPaths())
.libPaths()
# }
# NOT RUN {
# }
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