Implement custom debug function that shows post data

[hadley]

Should replace verbose().

• Needs option to turn informative messages on (not usually that helpful)
• Needs option to show data in/out
• Needs helper for nice indenting

library(httr)

update <- function(msg, type, curl)  {
  switch(type + 1, 
    text = NULL, # message("* ", msg, appendLF = FALSE),
    headerIn = message("<  ", msg, appendLF = FALSE),
    headerOut = message(">  ", msg, appendLF = FALSE),
    dataIn = NULL,
    dataOut = message(">> ", msg),
    sslDataIn = NULL,
    sslDataOut = NULL,
  )
}

my_verbose <- c(config(debugfunction = update), verbose())

b2 <- "http://httpbin.org/post"
x <- POST(b2, body = "A simple text string", my_verbose)
x <- POST(b2, body = list(x = "A simple text string"), my_verbose)
x <- POST(b2, body = list(x = "A simple text string"), my_verbose, multipart = FALSE)
x <- POST(b2, body = list(y = upload_file(system.file("CITATION"))), my_verbose)
x <- POST(b2, body = NULL, my_verbose)
x <- POST(b2, body = "", my_verbose)
x <- POST(b2, body = FALSE, my_verbose)