Listen very carefully. I shall say this only once.
Michelle Dubois, ’Allo ’Allo
onetime provides convenience functions to run R code
only once per user. For example, you can show a startup message only the
first time (ever) that a package is loaded.
For more information, see the website.
library(onetime)
ids <- paste0("onetime-readme-", sample(1e9, 4))
for (i in 1:5) {
cat("Loop ", i, " of 5\n")
onetime_do(cat("This command will only be run once.\n"), id = ids[1])
onetime_warning("This warning will only be shown once.", id = ids[2])
onetime_message("This message will only be shown once.", id = ids[3])
}
#> Loop 1 of 5
#> This command will only be run once.
#> Warning: This warning will only be shown once.
#> This message will only be shown once.
#> Loop 2 of 5
#> Loop 3 of 5
#> Loop 4 of 5
#> Loop 5 of 5
# Meanwhile, in a separate process:
library(callr)
result <- callr::r(function (ids) {
onetime::onetime_message("This message with an existing ID will not be shown.", id = ids[1])
onetime::onetime_message("This message with a new ID will be shown.", id = ids[4])
}, show = TRUE, args = list(ids = ids))
#> This message with a new ID will be shown.You can install the development version from GitHub with:
# install.packages("devtools")
devtools::install_github("hughjonesd/onetime")