不要在错误处理程序中再次调用停止函数，而是将其删除（可选地打印错误消息），否则失败时，它将再次运行停止函数，而不会尝试捕获更多错误。你也可以用类似的方式来警告：

Connect <-
  function() {
    Sys.sleep(0.1)
    X = runif(1)
    if (X < .5) stop("Oops too low!")
    if (X > 0.9) warning("This is a high X!")
    cat(X, "\n")
  } 

while (TRUE) {
  tryCatch({
    Connect()
  }, error = function(e) {
    cat("Error:", e$message, "\n")
  }, warning = function(w) {
    cat("Warning:", w$message, "\n")
  })
}
#> 0.8085583 
#> Error: Oops too low! 
#> Error: Oops too low! 
#> 0.6671211 
#> 0.7245536 
#> Error: Oops too low! 
#> Warning: This is a high X! 
#> 0.7840508 
...

while循环的另一种方法是创建一个安全调用函数，其中包含tryCatch语句，并在完成tryCatch语句时递归调用该函数：

safe_loop <- function() {
  tryCatch(
    Connect(),
    error = function(e) {
      cat("Error:", e$message, "\n")
    }, warning = function(w) {
      cat("Warning:", w$message, "\n")
    }
  )
  safe_loop()
}

safe_loop()
#> 0.6366205 
#> Warning: This is a high X! 
#> 0.5966964 
#> Error: Oops too low! 
#> 0.8586928 
#> Error: Oops too low! 
...

旁注-不要在finally语句中尝试递归调用

今天我学到了这个崩溃的R：

unquittable_recursion <- function() {
  tryCatch(Sys.sleep(1),
           finally = unquittable_recursion()
  )
}

unquittable_recursion()

更新-失败时重复

set.seed(100)

Connect <-
  function() {
    Sys.sleep(0.1)
    X = runif(1)
    if (X < .5) stop("Oops too low!")
    if (X > 0.9) warning("This is a high X!")
    cat(X, "\n")
  } 

safe_loop <- function() {
  tryCatch({
    failed <- TRUE
    Connect()
    failed <- FALSE
  },
  error = function(e) {
    cat("Error:", e$message, "\n")
  }, warning = function(w) {
    cat("Warning:", w$message, "\n")
  })
  if(failed) safe_loop()
}

safe_loop()
#> Error: Oops too low! 
#> Error: Oops too low! 
#> 0.5523224