There’s an interesting little function in R called
on.exit(). It can be used
in your own function to perform some side effect. For example, in addition to
returning a value, the following function uses
on.exit() to also print two messages.
Note what happens if we remove
add=TRUE from the second
We see “first” isn’t printed anymore.
To learn more about
on.exit(), refer to Hadley’s book “Advanced R,” which can be obtained from Amazon.