Le 25/01/2024 à 19:04, Berwin A Turlach a écrit :
On Thu, 25 Jan 2024 09:44:26 -0800
Henrik Bengtsson <henrik.bengts...@gmail.com> wrote:
On Thu, Jan 25, 2024 at 9:23 AM Berwin A Turlach
<berwin.turl...@gmail.com> wrote:
G'day Duncon,
Uups, apologies for the misspelling of your name Duncan. Fingers were
too fast. :)
[...]
But you could always code your example (not tested :-) ) along lines
similar to:
if( with(version, all(as.numeric(c(major, minor)) >= c(4, 1))) ){
## code that uses native pipe
}else{
cat("You have to upgrade to R >= 4.1.0 to run this example\n")
}
That will unfortunately not work in this case, because |> is part of
the new *syntax* that was introduced in R 4.1.0. Older versions of R
simply doesn't understand how to *parse* those two symbols next to
each other, e.g.
{R 4.1.0}> parse(text = "1:3 |> sum()")
expression(1:3 |> sum())
{R 4.0.5}> parse(text = "1:3 |> sum()")
Error in parse(text = "1:3 |> sum()") : <text>:1:6: unexpected '>'
1: 1:3 |>
^
In order for R to execute some code, it needs to be able to parse it
first. Only then, it can execute it. So, here, we're not even getting
past the parsing phase.
Well, not withstanding 'fortune(181)', you could code it as:
if( with(version, all(as.numeric(c(major, minor)) >= c(4, 1))) ){
cat(eval(parse(text="1:3 |> sum()")), "\n")
}else{
cat("You have to upgrade to R >= 4.1.0 to run this example\n")
}
By nitpicking a little bit, this test won't work for v5.0 as minor "0"
is less then "1". There are a more canonical ways to test the version
and send a message (or a 'warning()'):
if (getVersion() >= "4.1") {
cat(eval(parse(text="1:3 |> sum()")), "\n")
} else {
message("You have to upgrade to R >= 4.1.0 to run this example")
}
Best,
Serguei.
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