Examples of safely function

safely-demo.R

# safe wrapper for functions ---------------------------------------------------
safely <- function(fun) {
  function(...) {
    warn <- err <- NULL
    res <- withCallingHandlers(
      tryCatch(fun(...), error = function(e) {
        err <<- conditionMessage(e)
        NULL
      }),
      warning = function(w) {
        warn <<- append(warn, conditionMessage(w))
        invokeRestart("muffleWarning")
      }
    )
    list(res = res, warn = warn, err = err)
  }
}


# Individual examples ----------------------------------------------------------

# generate data and make safe functions
dat <- data.frame(x = 1:10, y = 1:10)
safe_glm <- safely(glm)
safe_glm_nb <- safely(MASS::glm.nb)

message("example 1 - no warnings or errors")
safe_glm(y ~ x, data = dat, family = "poisson")

message("example 2 - errors")
safe_glm(y ~ x, family = "poisson")

message("example 3 - warnings")
safe_glm_nb(y ~ x, data = dat)


# List example -----------------------------------------------------------------

# generate data and make safe function
funky <- function(x = "ok") {
    switch(
        x,
        ok = "Everything is good in the world",
        warning = {
            warning("1st warning")
            warning("2nd warning")
            "you still get a result but we capture all warnings"
        },
        stop("Aaaarrrghhh!!!!!!!!")
    )
}
safe_funky <- safely(funky)
dat <- c("ok", "warning", "chaos")

message("list example")
lapply(dat, safe_funky)