Hello,
Would it be possible to have a custom prompt when browser()'ing.
I have made a simple implementation of this (which is attached), the
basic idea is that instead of the hardcoded sprintf( "Browser[%d]>
",
browselevel), a call to the getBrowsePrompt is made, and obviously the
function is:
> getBrowsePrompt
function (level = 1, env = .GlobalEnv) {
sprintf("Browse[%d]> ", level)
}
<environment: namespace:base>
> debug( rnorm )
> rnorm( 10 )
debugging in: rnorm(10)
debug: .Internal(rnorm(n, mean, sd))
Browse[1]>
exiting from: rnorm(10)
[1] -0.496598526 -0.006482431 1.491833990 -2.602605734 -0.275479145
[6] -1.143580117 0.146797854 -0.529420397 0.823817647 -0.256676050
but then it can be masked so that a more informative prompt is given,
like this for example (showing the call stack)
> getBrowsePrompt
function( level = 1, env = .GlobalEnv){
calls <- sys.calls()
stack <- sapply( calls[-1], function(x) tryCatch(as.character(x[[1]]),
error=function(e) "?") )
sprintf( "Browse[%d] %s > ", level, paste( stack, collapse =
" -> ") )
}
> f()
debugging in: rnorm(10)
debug: .Internal(rnorm(n, mean, sd))
Browse[1] rnorm -> getBrowsePrompt >
exiting from: rnorm(10)
[1] -0.53854862 -1.42674850 -0.48391168 -0.23446819 -0.36863380 0.53803626
[7] 1.70176078 0.82984068 1.05101379 -0.03944557
Or this: printing the content of the environment we are browsing :
> getBrowsePrompt <- function( level = 1, env = .GlobalEnv ){
+ print( ls.str( envir = env) )
+ base:::getBrowsePrompt( level, env )
+ }
> f()
debugging in: rnorm(10)
debug: .Internal(rnorm(n, mean, sd))
mean : num 0
n : num 10
sd : num 1
Browse[1]>
exiting from: rnorm(10)
[1] 1.1112007 0.4921306 0.1747196 -0.2518565 -0.9342039 0.5930085
[7] -0.5961234 0.1153541 -0.6189056 0.1670318
This probably should rely on an option instead of relying on masking
functions. Also this opens a back door to the debugging system of R, but
I am not sure this is entirely a bad thing. (see
http://www.statistik.lmu.de/~eugster/soc09/#p5)
On the same note, what about having a function for the prompt, so that
(for example) we could show the current working directory, the memory
usage, ...
Romain
--
Romain Francois
Independent R Consultant
+33(0) 6 28 91 30 30
http://romainfrancois.blog.free.fr
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