Nothing
require(data.table)
# Tests the suppression of := output
# Since this tests autoprinting at the console, it needs to use the .Rout.save mechanism in R CMD check
DT = data.table(a=1:2) # Should print at console?
DT # yes
DT[1] # yes
DT[2,a:=3L] # no
DT # yes
DT[FALSE,a:=3L] # no
DT[a==4L,a:=5L] # no
DT[a %in% 4:8, a:=5L] # no
DT # yes
print(DT[2,a:=4L]) # yes, as of #6631
print(DT) # yes
if (TRUE) DT[2,a:=5L] # no. used to print before v1.9.5
if (TRUE) if (TRUE) DT[2,a:=6L] # no. used to print before v1.9.5
(function(){DT[2,a:=5L];NULL})() # print NULL
DT # no (from v1.9.5+). := suppresses next auto print (can't distinguish just "DT" symbol alone at the prompt)
DT # yes. 2nd time needed, or solutions below
(function(){DT[2,a:=5L];NULL})() # print NULL
DT[] # yes. guaranteed print
(function(){DT[2,a:=5L];NULL})() # print NULL
print(DT) # yes. restored in #6631 behavior that had changed in 1.9.6.
(function(){DT[2,a:=5L][];NULL})() # print NULL
DT # yes. i) function needs to add [] after last one, so that "DT" alone is guaranteed anyway
(function(){DT[2,a:=5L];DT[];NULL})() # print NULL
DT # yes. ii) or as a separate DT[] after the last := inside the function
DT2 = data.table(b=3:4) # no
(function(){DT[2,a:=6L];DT2[1,b:=7L];NULL})()
DT # yes. last := was on DT2 not DT
{DT[2,a:=6L];invisible()} # no
print(DT) # yes
(function(){print(DT[2,a:=7L]);print(DT);invisible()})() # yes*2
{print(DT[2,a:=8L]);print(DT);invisible()} # yes*2 as at prompt, again as of #6631
DT[1][,a:=9L] # no (was too tricky to detect that DT[1] is a new object). Simple rule is that := always doesn't print
DT[2,a:=10L][1] # yes
DT[1,a:=10L][1,a:=10L] # no
DT[,a:=as.integer(a)] # no
DT[1,a:=as.integer(a)] # no
DT[1,a:=10L][] # yes. ...[] == oops, forgot print(...)
# Test that error in := doesn't suppress next valid print, bug #2376
tryCatch(DT[,foo:=ColumnNameTypo], error=function(e) e$message) # error: not found.
DT # yes
DT # yes
# Regression test for auto-printing suppression in source(), #2369
local({
f = tempfile(fileext = ".R")
on.exit(unlink(f))
writeLines(c(
"library(data.table)",
"DT = data.table(a = 1)",
"DT[,a:=1]" # no
), f)
source(f, local = TRUE, echo = TRUE)
})
# child class of data.table doesn't induce unintended print, #3029
dt <- data.table(x = 1)
class(dt) <- c("foo", "data.table", "data.frame")
print.foo <- function(x, ...) {
NextMethod("print")
}
dt[, y := 1] # no
# withAutoprint() testing (since R3.4.0)
if (!exists("withAutoprint", baseenv())) {
q("no")
}
if (TRUE) withAutoprint({
DT # yes
DT[1L, 1L] # yes
DT[2L, a := 10L] # no
})
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