using an exists statement in R

Question

I have made a progress bar using the winProgressBar method in R. What I want to do is if someone instantiates my program while it is doing all of its processing, I want the current progress bar to close. I tried using a statement that says

if(exists(progressBar)) {
  close(progressBar);
}

but I get an error from the console that says

Error in exists(progressBar) : object 'progressBar' not found

I know that it will not exist during the first iteration of my program, but there is no reason that I can find that would make an if statement cause the program to crash.

Answer 1

If you read the help for exists you will see the following under Arguments

x a variable name (given as a character string).

So

exists('progressBar')

will return TRUE or FALSE.