R check if function in a package was called from the package fun or externally

Question

How can I check from within the package (exported) function if the current function execution has been called by the function from that package or it was called by external package / from global env.

My current approach, developed by experimenting:

myfun <- function(){
    current_call = sys.call()
    parent_call = sys.call(sys.parent())
    if(identical(current_call,parent_call) || !identical(environmentName(parent.env(environment(match.fun(parent_call[[1L]])))),"imports:mypkg")){
        cat("called externally\n")
    }
}

Seems to not handle anonymous functions constructed in the other packages which dependent on my package.
Not particularly devtools related but package development related which devtools address well.

Edit:
To goal is to invoke an action (cat() in above example) in any cases except the calls from my other functions within the same package.

Answer 1

Borrowing from data.table:::cedta, I put these two functions in a package called test

myfun <- function() {
  te <- topenv(parent.frame(1))
  if(isNamespace(te) && getNamespaceName(te) == "test") { # <-- "test" is the name of the package
    cat("called from my package\n")
  } else cat("Not called from my package\n")
}

tester <- function() {
  myfun()
}

After loading the test package, I get these results

test:::myfun()
#Not called from my package
test:::tester()
#called from my package