[Rd] stopifnot() does not stop at first non-TRUE argument

[Suharto Anggono Suharto Anggono]

switch(i, ...)
extracts 'i'-th argument in '...'. It is like
eval(as.name(paste0("..", i))) .

Just mentioning other things:
- For 'n',
n <- nargs()
can be used.
- sys.call() can be used in place of match.call() .
---------------------------
>>>>> peter dalgaard <pdalgd at gmail.com>
>>>>>     on Mon, 15 May 2017 16:28:42 +0200 writes:

    > I think Hervé's idea was just that if switch can evaluate arguments selectively, so can stopifnot(). But switch() is .Primitive, so does it from C. 

if he just meant that, then "yes, of course" (but not so interesting).

    > I think it is almost a no-brainer to implement a sequential stopifnot if dropping to C code is allowed. In R it gets trickier, but how about this:

Something like this, yes, that's close to what Serguei Sokol had proposed
(and of course I *do*  want to keep the current sophistication
 of stopifnot(), so this is really too simple)

    > Stopifnot <- function(...)
    > {
    > n <- length(match.call()) - 1
    > for (i in 1:n)
    > {
    > nm <- as.name(paste0("..",i))
    > if (!eval(nm)) stop("not all true")
    > }
    > }
    > Stopifnot(2+2==4)
    > Stopifnot(2+2==5, print("Hey!!!") == "Hey!!!")
    > Stopifnot(2+2==4, print("Hey!!!") == "Hey!!!")
    > Stopifnot(T,T,T,T,T,T,T,T,T,T,T,T,T,T,T,T,F,T)


    >> On 15 May 2017, at 15:37 , Martin Maechler <maechler at stat.math.ethz.ch> wrote:
    >> 
    >> I'm still curious about Hervé's idea on using  switch()  for the
    >> issue.

    > -- 
    > Peter Dalgaard, Professor,
    > Center for Statistics, Copenhagen Business School
    > Solbjerg Plads 3, 2000 Frederiksberg, Denmark
    > Phone: (+45)38153501
    > Office: A 4.23
    > Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com