Show the name of the parent function in the warning message

Question

I have a helper function for displaying warnings:

mywarn <- function() {
  warning("I warn you")
}

If I call the function directly, I get the name of the function where the error occurred:

mywarn()
> Warning message:
  In mywarn() : I warn you

However I want to use the warning function from within several other functions:

myfun <- function(x) {
  x <- x^2
  mywarn()
  x
}

But then it still shows the name of my warning function when warning is displayed:

myfun(10)
> Warning message:
  In mywarn() : I warn you

What is the best way to make the warning message display myfun instead of mywarn ?

Answer 1

The simplest way is by explicitly constructing a warning condition object with a suitable call object, and passing that to warning. This overrides the default logic which uses the calling function.

mywarn <- function (call = sys.call(sys.parent())) {
  warning(simpleWarning("I warn you", call))
}

myfun(10)

Warning message:
In myfun(10) : I warn you