Question

Is there any way to stop an R program without error?

For example I have a big source, defining several functions and after it there are some calls to the functions. It happens that I edit some function, and want the function definitions to be updated in R environment, but they are not actually called.

I defined a variable justUpdate and when it is TRUE want to stop the program just after function definitions.

ReadInput <- function(...) ...
Analyze <- function(...) ...
WriteOutput <- function(...) ...

if (justUpdate)
    stop()
# main body
x <- ReadInput()
y <- Analyze(x)
WriteOutput(y)

I have called stop() function, but the problem is that it prints an error message.

ctrl+c is another option, but I want to stop the source in specific line.

The problem with q() or quit() is that it terminates R session, but I would like to have the R session still open.

As @JoshuaUlrich proposed browser() can be another option, but still not perfect, because the source terminates in a new environment (i.e. the R prompt will change to Browser[1]> rather than >). Still we can press Q to quit it, but I am looking for the straightforward way.

Another option is to use if (! justUpdate) { main body } but it’s clearing the problem, not solving it.

Is there any better option?

Answer 1

You’re looking for the function browser.