Locates the odiff executable using a priority-based search:
User-specified path via
options(odiffr.path = "...")System PATH (
Sys.which("odiff"))Cached binary from
install_odiff()(orodiffr_update())
Details
Installing odiff. If odiff cannot be found and the R session is
interactive, find_odiff() (and so compare_images(), odiff_run() and
the other functions that need the binary) offers once per session to
download the latest odiff release to the user cache with
install_odiff(). Nothing is ever downloaded without asking: the offer is
never made in non-interactive sessions, while running tests with testthat,
while knitting, or during R CMD check. Set
options(odiffr.ask_install = FALSE) to turn the offer off. If the offer
is declined, find_odiff() signals an error explaining how to install
odiff. odiff_available() never makes the offer.
npm installs. Since odiff 4.4, npm install -g odiff-bin puts a
small Node.js launcher script on the PATH, which starts Node and then
spawns the native binary shipped in an @odiff/<platform>-<arch>
package. Starting Node adds tens of milliseconds to every comparison, so
when the odiff found on the PATH is such a launcher (a #! script that
runs node, or an npm .cmd/.ps1 wrapper on Windows), find_odiff()
looks for the native binary inside the npm installation and returns it
instead. For older odiff-bin releases, the native bin/odiff.exe inside
the package is used. If no native binary can be found, the launcher itself
is returned, so a working setup is never broken. The lookup is cached per
launcher path and redone when the launcher file changes.
Set options(odiffr.resolve_npm = FALSE) to disable this and always use
the PATH entry as-is. A path given via options(odiffr.path = ...) is
always used exactly as specified and is never resolved.
See also
odiff_info() to see which binary is used and whether it was
resolved from an npm launcher.
Examples
if (FALSE) { # \dontrun{
find_odiff()
# Use the npm launcher on the PATH as-is
options(odiffr.resolve_npm = FALSE)
find_odiff()
} # }