get browsing state in a function

Question

I have a function such as this one :

fun <- function() {
  browser()
  is_browsing()
} 

I would like to know what the code of is_browsin

Answer 1

This is not 100% what you are looking for, but perhaps you get an idea how to solve your problem? I am not familiar with C / C++ R-basics, but perhaps you can kind of overload base::browser()?

I hope this helps:

list.parent_env <- function() {
  ll <- list()
  n <- 1
  while (!environmentName(.GlobalEnv) %in% 
         environmentName(parent.frame(n))) {
    ll <- c(ll, parent.frame(n))
    n <- n + 1
  }
  return(ll)
}

listofenv2names <- function(env_list) {
  names <- unlist(lapply(c(1:length(env_list)), function(i) {
    attributes(env_list[[i]])$name
  }))
  return(names)
}

# https://stackoverflow.com/a/23891089/5784831
mybrowser <- function() {
  e <- parent.frame()
  attr(e, "name") <- "mybrowser_env"
  assign("mybrowser_env", 1,
         envir = parent.frame(),
         inherits = FALSE, immediate = TRUE)
  return(eval(quote(browser()), parent.frame()))
}

is_browsing <- function() {
  env_list <- list.parent_env()
  r <- "mybrowser_env" %in% listofenv2names(env_list)
  print(r)
  return(r)
}

subsubfun <- function() {
  print("subsubfun")
  b <- 2
  is_browsing()
  return(NULL)
}

subfun <- function() {
  print("subfun")
  a <- 1
  is_browsing()
  subsubfun()
  return(NULL)
}

fun1 <- function() {
  print("fun1")
  is_browsing()
  mybrowser()
  for (i in 1:10) {
    is_browsing()
  }
  is_browsing()
  subfun()
  
  return(NULL)
} 

fun2 <- function() {
  print("fun2")
  is_browsing()
  return(NULL)
}

fun1()
fun2()

Output looks good:

[1] "fun1"
[1] FALSE
Called from: eval(quote(browser()), parent.frame())
Browse[1]> c
[1] TRUE
[1] "subfun"
[1] TRUE
[1] "subsubfun"
[1] TRUE
[1] "fun2"
[1] FALSE