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

[Martin Maechler]

>>>>> William Dunlap <wdun...@tibco.com>
>>>>> on Fri, 19 May 2017 09:30:42 -0700 writes:

> While you are fiddling with stopifnot(), please consider changing the form
> of the error thrown so that it includes the caller's call.  The change
> would be from something like
>   stop( <> )
> to
>   stop(simpleError( <>, sys.call(-1)))

> For the following code
>   f <- function(x, y) {
> stopifnot(x > y)
> x - y
>   }
>   g <- function(x, y, z) {
>  c(f(x, y), f(y, z))
>   }
>   g(6,3,4)

> you would see
>   Error in f(y, z) : x > y is not TRUE
> instead of the less informative
>   Error: x > y is not TRUE

well, yes, I have been fiddling .. ;-)

and your proposal above is quite remarkable!
I hadn't been aware of (the consequence of) this possibility.

I will do that change in addition to the planned ones, just to
make the changes slightly more modular.
(It will need a change in   tests/isas-tests.Rout.save  as
indeed, the _messages_ of non-toplevel  stopifnot() calls will
change too.
This may affect package checks check for the _wording_ of
stopifnot error messages [which may not be the best idea
.. though understandable for regression checks].

Martin


> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com

> On Fri, May 19, 2017 at 5:31 AM, Martin Maechler 
<maech...@stat.math.ethz.ch
>> wrote:

>> >>>>> Suharto Anggono Suharto Anggono via R-devel <r-devel@r-project.org>
>> >>>>> on Thu, 18 May 2017 16:27:09 + writes:
>> 
>> >> From an example in
>> 
>> >> http://www.uni-muenster.de/ZIV.BennoSueselbeck/s-html/
>> helpfiles/nargs.html
>> >> , number of arguments in '...' can be obtained by
>> 
>> > (function(...)nargs())(...) .
>> 
>> neat and good.  Though really is not exactly "well readable".
>> 
>> In the mean time, there is   ...length()   in R-devel [somewhat
>> experimentally]
>> 
>> > I now realize that sys.call() doesn't expand '...' when
>> > the function is called with '...'. It just returns the call as is.
>> yes.
>> > If 'stopifnot' uses sys.call() instead of
>> > match.call() , the following example behaves improperly:
>> 
>> > g <- function(...) stopifnot(...)
>> > g(TRUE, FALSE)
>> 
>> Indeed.  Very improperly (it does not stop).
>> 
>> However, calling stopifnot() with a '...' passed from above is
>> not a very good idea anyway, because stopifnot has to assume it
>> is called with explicit expressions.
>> Hence we have
>> 
>> > g <- function(...) stopifnot(...) ;  g(1 == 1, 3 < 1)
>> Error: ..2 is not TRUE
    >> 
>> {and to "fix" this, e.g., with an extra optional argument} would
>> lead to more complications  which I really think we do not want}.
>> 
>> But the example does show we should keep match.call().
>> Martin
>> 
>> > 
>> > On Thu, 18/5/17, Martin Maechler
>> > <maech...@stat.math.ethz.ch> wrote:
>> 
>> >  Subject: Re: [Rd] stopifnot() does not stop at first
>> > non-TRUE argument
>> 
>> >  Cc: r-devel@r-project.org Date: Thursday, 18 May, 2017,
>> > 3:03 PM
>> 
>> >>>>> Suharto Anggono Suharto Anggono via R-devel  
>> >>>>> on Tue, 16 May 2017 16:37:45 + writes:
>> 
>> >> switch(i, ...)  extracts 'i'-th argument in '...'. It is
>> >> like eval(as.name(paste0("..", i))) .
>> 
>> > Yes, that's neat.
>> 
>> > It is only almost the same: in the case of illegal 'i' the
>> > switch() version returns invisible(NULL)
>> 
>> > whereas the version we'd want should signal an error,
>> > typically the same error message as
>> 
>> >> t2 <- function(...) ..2 t2(1)
>> >   Error in t2(1) (from #1) : the ... list does not contain
>> > 2 elements
>> >>
>> 
>> 
>> >> Just mentioning other things: - For 'n', n <- nargs() can
>> >> be used.
>> 
>> > I know .. [in this case, where '...' is the only formal
>> > argument of the function]
>> 
>> >> - sys.call() can be used in place of match.call() .
>> 
>> > Hmm... in many cases, yes notably, as we do *not* want
>> > the argument names here, I think you are right.
>> 
>> > __
>> > R-devel@r-project.org mailing list
>> > https://stat.ethz.ch/mailman/listinfo/r-devel
>> 
>> __
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>> 

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

[William Dunlap via R-devel]

While you are fiddling with stopifnot(), please consider changing the form
of the error thrown so that it includes the caller's call.  The change
would be from something like
  stop( <> )
to
  stop(simpleError( <>, sys.call(-1)))

For the following code
  f <- function(x, y) {
  stopifnot(x > y)
  x - y
  }
  g <- function(x, y, z) {
  c(f(x, y), f(y, z))
  }
  g(6,3,4)
you would see
  Error in f(y, z) : x > y is not TRUE
instead of the less informative
  Error: x > y is not TRUE



Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Fri, May 19, 2017 at 5:31 AM, Martin Maechler <maech...@stat.math.ethz.ch
> wrote:

> >>>>> Suharto Anggono Suharto Anggono via R-devel <r-devel@r-project.org>
> >>>>> on Thu, 18 May 2017 16:27:09 + writes:
>
> >> From an example in
>
> >> http://www.uni-muenster.de/ZIV.BennoSueselbeck/s-html/
> helpfiles/nargs.html
> >> , number of arguments in '...' can be obtained by
>
> > (function(...)nargs())(...) .
>
> neat and good.  Though really is not exactly "well readable".
>
> In the mean time, there is   ...length()   in R-devel [somewhat
> experimentally]
>
> > I now realize that sys.call() doesn't expand '...' when
> > the function is called with '...'. It just returns the call as is.
> yes.
> > If 'stopifnot' uses sys.call() instead of
> > match.call() , the following example behaves improperly:
>
> > g <- function(...) stopifnot(...)
> > g(TRUE, FALSE)
>
> Indeed.  Very improperly (it does not stop).
>
> However, calling stopifnot() with a '...' passed from above is
> not a very good idea anyway, because stopifnot has to assume it
> is called with explicit expressions.
> Hence we have
>
>   > g <- function(...) stopifnot(...) ;  g(1 == 1, 3 < 1)
>   Error: ..2 is not TRUE
>
> {and to "fix" this, e.g., with an extra optional argument} would
>  lead to more complications  which I really think we do not want}.
>
> But the example does show we should keep match.call().
> Martin
>
> > 
> > On Thu, 18/5/17, Martin Maechler
> > <maech...@stat.math.ethz.ch> wrote:
>
> >  Subject: Re: [Rd] stopifnot() does not stop at first
> > non-TRUE argument
>
> >  Cc: r-devel@r-project.org Date: Thursday, 18 May, 2017,
> > 3:03 PM
>
> >>>>> Suharto Anggono Suharto Anggono via R-devel  r-project.org>
> >>>>> on Tue, 16 May 2017 16:37:45 + writes:
>
> >> switch(i, ...)  extracts 'i'-th argument in '...'. It is
> >> like eval(as.name(paste0("..", i))) .
>
> > Yes, that's neat.
>
> > It is only almost the same: in the case of illegal 'i' the
> > switch() version returns invisible(NULL)
>
> > whereas the version we'd want should signal an error,
> > typically the same error message as
>
> >> t2 <- function(...) ..2 t2(1)
> >   Error in t2(1) (from #1) : the ... list does not contain
> > 2 elements
> >>
>
>
> >> Just mentioning other things: - For 'n', n <- nargs() can
> >> be used.
>
> > I know .. [in this case, where '...' is the only formal
> > argument of the function]
>
> >> - sys.call() can be used in place of match.call() .
>
> > Hmm... in many cases, yes notably, as we do *not* want
> > the argument names here, I think you are right.
>
> > __
> > R-devel@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
>
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>

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

[Martin Maechler]

>>>>> Suharto Anggono Suharto Anggono via R-devel <r-devel@r-project.org>
>>>>> on Thu, 18 May 2017 16:27:09 + writes:

>> From an example in

>> 
http://www.uni-muenster.de/ZIV.BennoSueselbeck/s-html/helpfiles/nargs.html
>> , number of arguments in '...' can be obtained by

> (function(...)nargs())(...) .

neat and good.  Though really is not exactly "well readable".

In the mean time, there is   ...length()   in R-devel [somewhat experimentally]

> I now realize that sys.call() doesn't expand '...' when
> the function is called with '...'. It just returns the call as is.
yes.
> If 'stopifnot' uses sys.call() instead of
> match.call() , the following example behaves improperly: 

> g <- function(...) stopifnot(...)
> g(TRUE, FALSE)

Indeed.  Very improperly (it does not stop).

However, calling stopifnot() with a '...' passed from above is
not a very good idea anyway, because stopifnot has to assume it
is called with explicit expressions.
Hence we have

  > g <- function(...) stopifnot(...) ;  g(1 == 1, 3 < 1)
  Error: ..2 is not TRUE

{and to "fix" this, e.g., with an extra optional argument} would
 lead to more complications  which I really think we do not want}.

But the example does show we should keep match.call().
Martin

> ------------
> On Thu, 18/5/17, Martin Maechler
> <maech...@stat.math.ethz.ch> wrote:

>  Subject: Re: [Rd] stopifnot() does not stop at first
> non-TRUE argument

>  Cc: r-devel@r-project.org Date: Thursday, 18 May, 2017,
> 3:03 PM
 
>>>>> Suharto Anggono Suharto Anggono via R-devel 
>>>>> on Tue, 16 May 2017 16:37:45 + writes:

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

> Yes, that's neat.

> It is only almost the same: in the case of illegal 'i' the
> switch() version returns invisible(NULL)

> whereas the version we'd want should signal an error,
> typically the same error message as

>> t2 <- function(...) ..2 t2(1)
>   Error in t2(1) (from #1) : the ... list does not contain
> 2 elements
>> 


>> Just mentioning other things: - For 'n', n <- nargs() can
>> be used.

> I know .. [in this case, where '...' is the only formal
> argument of the function]

>> - sys.call() can be used in place of match.call() .

> Hmm... in many cases, yes notably, as we do *not* want
> the argument names here, I think you are right.

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

[Suharto Anggono Suharto Anggono via R-devel]

>From an example in 
>http://www.uni-muenster.de/ZIV.BennoSueselbeck/s-html/helpfiles/nargs.html , 
>number of arguments in '...' can be obtained by
(function(...)nargs())(...) .

I now realize that sys.call() doesn't expand '...' when the function is called 
with '...'. It just returns the call as is. If 'stopifnot' uses sys.call() 
instead of match.call() , the following example behaves improperly:
g <- function(...) stopifnot(...)
g(TRUE, FALSE)


On Thu, 18/5/17, Martin Maechler <maech...@stat.math.ethz.ch> wrote:

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

 Cc: r-devel@r-project.org
 Date: Thursday, 18 May, 2017, 3:03 PM
 
>>>>> Suharto Anggono Suharto Anggono via R-devel 
>>>>> on Tue, 16 May 2017 16:37:45 + writes:

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

Yes, that's neat.

It is only almost the same:  in the case of illegal 'i'
the switch() version returns
invisible(NULL)

whereas the version we'd want should signal an error, typically
the same error message as

  > t2 <- function(...) ..2
  > t2(1)
  Error in t2(1) (from #1) : the ... list does not contain 2 elements
  > 


> Just mentioning other things:
> - For 'n',
> n <- nargs()
> can be used.

I know .. [in this case, where '...' is the only formal argument of the 
function]

> - sys.call() can be used in place of match.call() .

Hmm... in many cases, yes notably, as we do *not* want the
argument names here, I think you are right.

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

[Martin Maechler]

> Suharto Anggono Suharto Anggono via R-devel 
> on Tue, 16 May 2017 16:37:45 + writes:

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

Yes, that's neat.

It is only almost the same:  in the case of illegal 'i'
the switch() version returns
invisible(NULL)

whereas the version we'd want should signal an error, typically
the same error message as

  > t2 <- function(...) ..2
  > t2(1)
  Error in t2(1) (from #1) : the ... list does not contain 2 elements
  > 


> Just mentioning other things:
> - For 'n',
> n <- nargs()
> can be used.

I know .. [in this case, where '...' is the only formal argument of the 
function]

> - sys.call() can be used in place of match.call() .

Hmm... in many cases, yes notably, as we do *not* want the
argument names here, I think you are right.


> ---
> peter dalgaard 
> 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  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

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

[Hervé Pagès]

On 05/16/2017 09:59 AM, peter dalgaard wrote:



On 16 May 2017, at 18:37 , Suharto Anggono Suharto Anggono via R-devel 
 wrote:

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


Hey, that's pretty neat!


Indeed! Seems like this topic is even more connected to switch()
than I anticipated...

H.



-pd



Just mentioning other things:
- For 'n',
n <- nargs()
can be used.
- sys.call() can be used in place of match.call() .
---

peter dalgaard 
   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  
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


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--
Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpa...@fredhutch.org
Phone:  (206) 667-5791
Fax:(206) 667-1319

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

[Martin Maechler]

>   
> on Tue, 16 May 2017 09:49:56 -0500 writes:

> On Tue, 16 May 2017, Martin Maechler wrote:
>>> Hervé Pagès 
>>> on Mon, 15 May 2017 16:54:46 -0700 writes:
>> 
>> > Hi,
>> > On 05/15/2017 10:41 AM, luke-tier...@uiowa.edu wrote:
>> >> This is getting pretty convoluted.
>> >>
>> >> The current behavior is consistent with the description at the top of
>> >> the help page -- it does not promise to stop evaluation once the first
>> >> non-TRUE is found.  That seems OK to me -- if you want sequencing you
>> >> can use
>> >>
>> >> stopifnot(A)
>> >> stopifnot(B)
>> >>
>> >> or
>> >>
>> >> stopifnot(A && B)
>> 
>> > My main use case for using stopifnot() is argument checking. In that
>> > context, I like the conciseness of
>> 
>> > stopifnot(
>> > A,
>> > B,
>> > ...
>> > )
>> 
>> > I think it's a common use case (and a pretty natural thing to do) to
>> > order/organize the expressions in a way such that it only makes sense
>> > to continue evaluating if all was OK so far e.g.
>> 
>> > stopifnot(
>> > is.numeric(x),
>> > length(x) == 1,
>> > is.na(x)
>> > )
>> 
>> I agree.  And that's how I have used stopifnot() in many cases
>> myself, sometimes even more "extremely" than the above example,
>> using assertions that only make sense if previous assertions
>> were fulfilled, such as
>> 
>> stopifnot(is.numeric(n), length(n) == 1, n == round(n), n >= 0)
>> 
>> or in the Matrix package, first checking some class properties
>> and then things that only make sense for objects with those properties.
>> 
>> 
>> > At least that's how things are organized in the stopifnot() calls that
>> > accumulated in my code over the years. That's because I was convinced
>> > that evaluation would stop at the first non-true expression (as
>> > suggested by the man page). Until recently when I got a warning issued
>> > by an expression located *after* the first non-true expression. This
>> > was pretty unexpected/confusing!
>> 
>> > If I can't rely on this "sequencing" feature, I guess I can always
>> > do
>> 
>> > stopifnot(A)
>> > stopifnot(B)
>> > ...
>> 
>> > but I loose the conciseness of calling stopifnot() only once.
>> > I could also use
>> 
>> > stopifnot(A && B && ...)
>> 
>> > but then I loose the conciseness of the error message i.e. it's going
>> > to be something like
>> 
>> > Error: A && B && ... is not TRUE
>> 
>> > which can be pretty long/noisy compared to the message that reports
>> > only the 1st error.
>> 
>> 
>> > Conciseness/readability of the single call to stopifnot() and
>> > conciseness of the error message are the features that made me
>> > adopt stopifnot() in the 1st place.
>> 
>> Yes, and that had been my design goal when I created it.
>> 
>> I do tend agree with  Hervé and Serguei here.
>> 
>> > If stopifnot() cannot be revisited
>> > to do "sequencing" then that means I will need to revisit all my calls
>> > to stopifnot().
>> 
>> >>
>> >> I could see an argument for a change that in the multiple argumetn
>> >> case reports _all_ that fail; that would seem more useful to me than
>> >> twisting the code into knots.
>> 
>> Interesting... but really differing from the current documentation,
>> 
>> > Why not. Still better than the current situation. But only if that
>> > semantic seems more useful to people. Would be sad if usefulness
>> > of one semantic or the other was decided based on trickiness of
>> > implementation.
>> 
>> Well, the trickiness  should definitely play a role.
>> Apart from functionality and semantics, long term maintenance
>> and code readibility, even elegance have shown to be very
>> important aspects of good code in ca 30 years of S and R programming.
>> 
>> OTOH, as mentioned above, the creation of good error messages
>> has been an important design goal of  stopifnot()  and hence I'm
>> willing to accept the extra complexity of "patching up" the call
>> used in the error / warning messages.
>> 
>> Also, as a change to what I posted yesterday, I now plan to follow
>> Peter Dalgaard's suggestion of using
>> eval( .. )
>> instead of   eval(cl[[i]], envir = )
>> as there may be cases where the former behaves better in lazy
>> evaluation situations.
>> (Other opinions on that ?)

> If you go this route it would be useful to step back and think about
> whether there might be some useful primitives to add to make this
> easier, such as

> - provide a dotsLength function for computing the number arguments
> captured 

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

[Suharto Anggono Suharto Anggono via R-devel]

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 
> 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  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

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

[luke-tierney]

On Tue, 16 May 2017, Martin Maechler wrote:


Hervé Pagès 
on Mon, 15 May 2017 16:54:46 -0700 writes:


   > Hi,
   > On 05/15/2017 10:41 AM, luke-tier...@uiowa.edu wrote:
   >> This is getting pretty convoluted.
   >>
   >> The current behavior is consistent with the description at the top of
   >> the help page -- it does not promise to stop evaluation once the first
   >> non-TRUE is found.  That seems OK to me -- if you want sequencing you
   >> can use
   >>
   >> stopifnot(A)
   >> stopifnot(B)
   >>
   >> or
   >>
   >> stopifnot(A && B)

   > My main use case for using stopifnot() is argument checking. In that
   > context, I like the conciseness of

   > stopifnot(
   > A,
   > B,
   > ...
   > )

   > I think it's a common use case (and a pretty natural thing to do) to
   > order/organize the expressions in a way such that it only makes sense
   > to continue evaluating if all was OK so far e.g.

   > stopifnot(
   > is.numeric(x),
   > length(x) == 1,
   > is.na(x)
   > )

I agree.  And that's how I have used stopifnot() in many cases
myself, sometimes even more "extremely" than the above example,
using assertions that only make sense if previous assertions
were fulfilled, such as

   stopifnot(is.numeric(n), length(n) == 1, n == round(n), n >= 0)

or in the Matrix package, first checking some class properties
and then things that only make sense for objects with those properties.


   > At least that's how things are organized in the stopifnot() calls that
   > accumulated in my code over the years. That's because I was convinced
   > that evaluation would stop at the first non-true expression (as
   > suggested by the man page). Until recently when I got a warning issued
   > by an expression located *after* the first non-true expression. This
   > was pretty unexpected/confusing!

   > If I can't rely on this "sequencing" feature, I guess I can always
   > do

   > stopifnot(A)
   > stopifnot(B)
   > ...

   > but I loose the conciseness of calling stopifnot() only once.
   > I could also use

   > stopifnot(A && B && ...)

   > but then I loose the conciseness of the error message i.e. it's going
   > to be something like

   > Error: A && B && ... is not TRUE

   > which can be pretty long/noisy compared to the message that reports
   > only the 1st error.


   > Conciseness/readability of the single call to stopifnot() and
   > conciseness of the error message are the features that made me
   > adopt stopifnot() in the 1st place.

Yes, and that had been my design goal when I created it.

I do tend agree with  Hervé and Serguei here.

   > If stopifnot() cannot be revisited
   > to do "sequencing" then that means I will need to revisit all my calls
   > to stopifnot().

   >>
   >> I could see an argument for a change that in the multiple argumetn
   >> case reports _all_ that fail; that would seem more useful to me than
   >> twisting the code into knots.

Interesting... but really differing from the current documentation,

   > Why not. Still better than the current situation. But only if that
   > semantic seems more useful to people. Would be sad if usefulness
   > of one semantic or the other was decided based on trickiness of
   > implementation.

Well, the trickiness  should definitely play a role.
Apart from functionality and semantics, long term maintenance
and code readibility, even elegance have shown to be very
important aspects of good code in ca 30 years of S and R programming.

OTOH, as mentioned above, the creation of good error messages
has been an important design goal of  stopifnot()  and hence I'm
willing to accept the extra complexity of "patching up" the call
used in the error / warning messages.

Also, as a change to what I posted yesterday, I now plan to follow
Peter Dalgaard's suggestion of using
eval( .. )
instead of   eval(cl[[i]], envir = )
as there may be cases where the former behaves better in lazy
evaluation situations.
(Other opinions on that ?)


If you go this route it would be useful to step back and think about
whether there might be some useful primitives to add to make this
easier, such as

- provide a dotsLength function for computing the number arguments
  captured in a ... argument

- providing a dotsElt function for extracting the i-the element
  instead of going through the eval(sprintf("..%d", i)) construct.

- maybe something for extracting the expression for the i-th argument.

The might be more generally useful and make the code more readable and
maintainable.

Best,

luke



Martin

   > Thanks,
   > H.

   >>
   >> Best,
   >>
   >> luke
   >>
   >> On Mon, 15 May 2017, Martin Maechler wrote:
   >>
    Serguei Sokol 
    on Mon, 15 May 2017 16:32:20 +0200 writes:
   >>>
   >>> > Le 15/05/2017 à 15:37, Martin Maechler a écrit :
   >>> >>> Serguei Sokol 
   >>> >>> on Mon, 15 May 2017 13:14:34 +0200 writes:
   >>> >> 

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

[luke-tierney]

On Tue, 16 May 2017, Serguei Sokol wrote:


Le 15/05/2017 à 19:41, luke-tier...@uiowa.edu a écrit :

This is getting pretty convoluted.

The current behavior is consistent with the description at the top of
the help page -- it does not promise to stop evaluation once the first
non-TRUE is found.

Hm... we can read in the man page :
‘stopifnot(A, B)’ is conceptually equivalent to

 { if(any(is.na(A)) || !all(A)) stop(...);
   if(any(is.na(B)) || !all(B)) stop(...) }
and this behavior does promise to stop at first non-TRUE value
without evaluation of the rest of conditions.


Yes: that is why I explicitly referenced the description at the top of
the page.

Changing the 'conceptually equivalent' bit to reflect what is
happening is easy.  The changes being discussed, and their long term
maintenance, ar not.

Best,

luke




Sergueï.



--
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa  Phone: 319-335-3386
Department of Statistics andFax:   319-335-3017
   Actuarial Science
241 Schaeffer Hall  email:   luke-tier...@uiowa.edu
Iowa City, IA 52242 WWW:  http://www.stat.uiowa.edu
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Re: [Rd] stopifnot() does not stop at first non-TRUE argument

[Serguei Sokol]

Le 15/05/2017 à 19:41, luke-tier...@uiowa.edu a écrit :

This is getting pretty convoluted.

The current behavior is consistent with the description at the top of
the help page -- it does not promise to stop evaluation once the first
non-TRUE is found.

Hm... we can read in the man page :
‘stopifnot(A, B)’ is conceptually equivalent to

  { if(any(is.na(A)) || !all(A)) stop(...);
if(any(is.na(B)) || !all(B)) stop(...) }
and this behavior does promise to stop at first non-TRUE value
without evaluation of the rest of conditions.

Sergueï.

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

[Martin Maechler]

> Hervé Pagès 
> on Mon, 15 May 2017 16:54:46 -0700 writes:

> Hi,
> On 05/15/2017 10:41 AM, luke-tier...@uiowa.edu wrote:
>> This is getting pretty convoluted.
>> 
>> The current behavior is consistent with the description at the top of
>> the help page -- it does not promise to stop evaluation once the first
>> non-TRUE is found.  That seems OK to me -- if you want sequencing you
>> can use
>> 
>> stopifnot(A)
>> stopifnot(B)
>> 
>> or
>> 
>> stopifnot(A && B)

> My main use case for using stopifnot() is argument checking. In that
> context, I like the conciseness of

> stopifnot(
> A,
> B,
> ...
> )

> I think it's a common use case (and a pretty natural thing to do) to
> order/organize the expressions in a way such that it only makes sense
> to continue evaluating if all was OK so far e.g.

> stopifnot(
> is.numeric(x),
> length(x) == 1,
> is.na(x)
> )

I agree.  And that's how I have used stopifnot() in many cases
myself, sometimes even more "extremely" than the above example,
using assertions that only make sense if previous assertions
were fulfilled, such as

stopifnot(is.numeric(n), length(n) == 1, n == round(n), n >= 0)

or in the Matrix package, first checking some class properties
and then things that only make sense for objects with those properties.


> At least that's how things are organized in the stopifnot() calls that
> accumulated in my code over the years. That's because I was convinced
> that evaluation would stop at the first non-true expression (as
> suggested by the man page). Until recently when I got a warning issued
> by an expression located *after* the first non-true expression. This
> was pretty unexpected/confusing!

> If I can't rely on this "sequencing" feature, I guess I can always
> do

> stopifnot(A)
> stopifnot(B)
> ...

> but I loose the conciseness of calling stopifnot() only once.
> I could also use

> stopifnot(A && B && ...)

> but then I loose the conciseness of the error message i.e. it's going
> to be something like

> Error: A && B && ... is not TRUE

> which can be pretty long/noisy compared to the message that reports
> only the 1st error.


> Conciseness/readability of the single call to stopifnot() and
> conciseness of the error message are the features that made me
> adopt stopifnot() in the 1st place. 

Yes, and that had been my design goal when I created it.

I do tend agree with  Hervé and Serguei here.

> If stopifnot() cannot be revisited
> to do "sequencing" then that means I will need to revisit all my calls
> to stopifnot().

>> 
>> I could see an argument for a change that in the multiple argumetn
>> case reports _all_ that fail; that would seem more useful to me than
>> twisting the code into knots.

Interesting... but really differing from the current documentation,

> Why not. Still better than the current situation. But only if that
> semantic seems more useful to people. Would be sad if usefulness
> of one semantic or the other was decided based on trickiness of
> implementation.

Well, the trickiness  should definitely play a role.
Apart from functionality and semantics, long term maintenance
and code readibility, even elegance have shown to be very
important aspects of good code in ca 30 years of S and R programming.

OTOH, as mentioned above, the creation of good error messages
has been an important design goal of  stopifnot()  and hence I'm
willing to accept the extra complexity of "patching up" the call
used in the error / warning messages.

Also, as a change to what I posted yesterday, I now plan to follow
Peter Dalgaard's suggestion of using
 eval( .. ) 
instead of   eval(cl[[i]], envir = )
as there may be cases where the former behaves better in lazy
evaluation situations.
(Other opinions on that ?)

Martin

> Thanks,
> H.

>> 
>> Best,
>> 
>> luke
>> 
>> On Mon, 15 May 2017, Martin Maechler wrote:
>> 
 Serguei Sokol 
 on Mon, 15 May 2017 16:32:20 +0200 writes:
>>> 
>>> > Le 15/05/2017 à 15:37, Martin Maechler a écrit :
>>> >>> Serguei Sokol 
>>> >>> on Mon, 15 May 2017 13:14:34 +0200 writes:
>>> >> > I see in the archives that the attachment cannot pass.
>>> >> > So, here is the code:
>>> >>
>>> >> [... MM: I needed to reformat etc to match closely to
>>> >> the current source code which is in
>>> >>
>>> 

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

[Hervé Pagès]

On 05/15/2017 07:28 AM, peter dalgaard wrote:

I think Hervé's idea was just that if switch can evaluate arguments 
selectively, so can stopifnot().


Yep.

Thanks,
H.


But switch() is .Primitive, so does it from C.

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:

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  wrote:

I'm still curious about Hervé's idea on using  switch()  for the
issue.




--
Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpa...@fredhutch.org
Phone:  (206) 667-5791
Fax:(206) 667-1319

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

[Hervé Pagès]

Hi,

On 05/15/2017 10:41 AM, luke-tier...@uiowa.edu wrote:

This is getting pretty convoluted.

The current behavior is consistent with the description at the top of
the help page -- it does not promise to stop evaluation once the first
non-TRUE is found.  That seems OK to me -- if you want sequencing you
can use

stopifnot(A)
stopifnot(B)

or

stopifnot(A && B)


My main use case for using stopifnot() is argument checking. In that
context, I like the conciseness of

  stopifnot(
A,
B,
...
  )

I think it's a common use case (and a pretty natural thing to do) to
order/organize the expressions in a way such that it only makes sense
to continue evaluating if all was OK so far e.g.

  stopifnot(
is.numeric(x),
length(x) == 1,
is.na(x)
  )

At least that's how things are organized in the stopifnot() calls that
accumulated in my code over the years. That's because I was convinced
that evaluation would stop at the first non-true expression (as
suggested by the man page). Until recently when I got a warning issued
by an expression located *after* the first non-true expression. This
was pretty unexpected/confusing!

If I can't rely on this "sequencing" feature, I guess I can always
do

  stopifnot(A)
  stopifnot(B)
  ...

but I loose the conciseness of calling stopifnot() only once.
I could also use

  stopifnot(A && B && ...)

but then I loose the conciseness of the error message i.e. it's going
to be something like

  Error: A && B && ... is not TRUE

which can be pretty long/noisy compared to the message that reports
only the 1st error.

Conciseness/readability of the single call to stopifnot() and
conciseness of the error message are the features that made me
adopt stopifnot() in the 1st place. If stopifnot() cannot be revisited
to do "sequencing" then that means I will need to revisit all my calls
to stopifnot().



I could see an argument for a change that in the multiple argumetn
case reports _all_ that fail; that would seem more useful to me than
twisting the code into knots.


Why not. Still better than the current situation. But only if that
semantic seems more useful to people. Would be sad if usefulness
of one semantic or the other was decided based on trickiness of
implementation.

Thanks,
H.



Best,

luke

On Mon, 15 May 2017, Martin Maechler wrote:


Serguei Sokol 
on Mon, 15 May 2017 16:32:20 +0200 writes:


   > Le 15/05/2017 à 15:37, Martin Maechler a écrit :
   >>> Serguei Sokol 
   >>> on Mon, 15 May 2017 13:14:34 +0200 writes:
   >> > I see in the archives that the attachment cannot pass.
   >> > So, here is the code:
   >>
   >> [... MM: I needed to reformat etc to match closely to
   >> the current source code which is in
   >>
https://urldefense.proofpoint.com/v2/url?u=https-3A__svn.r-2Dproject.org_R_trunk_src_library_base_R_stop.R=DwIFAw=eRAMFD45gAfqt84VtBcfhQ=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA=t9fJDOl9YG2zB-GF0wQXrXJTsW2jxTxMHE-qZfLGzHU=KGsvpXrXpHCFTdbLM9ci3sBNO9C3ocsgEqHMvZKvV9I=
   >> or its corresponding github mirror
   >>
https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_wch_r-2Dsource_blob_trunk_src_library_base_R_stop.R=DwIFAw=eRAMFD45gAfqt84VtBcfhQ=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA=t9fJDOl9YG2zB-GF0wQXrXJTsW2jxTxMHE-qZfLGzHU=7Z5bPVWdGPpY2KLnXQP6c-_8s86CpKe0ZYkCfqjfxY0=
   >> ]
   >>
   >> > Best,
   >> > Serguei.
   >>
   >> Yes, something like that seems even simpler than Peter's
   >> suggestion...
   >>
   >> It currently breaks 'make check' in the R sources,
   >> specifically in tests/reg-tests-2.R (lines 6574 ff),
   >> the new code now gives
   >>
   >> > ## error messages from (C-level) evalList
   >> > tst <- function(y) { stopifnot(is.numeric(y)); y+ 1 }
   >> > try(tst())
   >> Error in eval(cl.i, pfr) : argument "y" is missing, with no default
   >>
   >> whereas previously it gave
   >>
   >> Error in stopifnot(is.numeric(y)) :
   >> argument "y" is missing, with no default
   >>
   >>
   >> But I think that change (of call stack in such an error case) is
   >> unavoidable and not a big problem.

   > It can be avoided but at price of customizing error() and
warning() calls with something like:
   > wrn <- function(w) {w$call <- cl.i; warning(w)}
   > err <- function(e) {e$call <- cl.i; stop(e)}
   > ...
   > tryCatch(r <- eval(cl.i, pfr), warning=wrn, error=err)

   > Serguei.

Well, a good idea, but the 'warning' case is more complicated
(and the above incorrect): I do want the warning there, but
_not_ return the warning, but rather, the result of eval() :
So this needs even more sophistication, using  withCallingHandlers(.)
and maybe that really get's too sophisticated and no
more "readable" to 99.9% of the R users ... ?

I now do append my current version -- in case some may want to
comment or improve further.

Martin






--
Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research 

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

[luke-tierney]

This is getting pretty convoluted.

The current behavior is consistent with the description at the top of
the help page -- it does not promise to stop evaluation once the first
non-TRUE is found.  That seems OK to me -- if you want sequencing you
can use

stopifnot(A)
stopifnot(B)

or

stopifnot(A && B)

I could see an argument for a change that in the multiple argumetn
case reports _all_ that fail; that would seem more useful to me than
twisting the code into knots.

Best,

luke

On Mon, 15 May 2017, Martin Maechler wrote:


Serguei Sokol 
on Mon, 15 May 2017 16:32:20 +0200 writes:


   > Le 15/05/2017 à 15:37, Martin Maechler a écrit :
   >>> Serguei Sokol 
   >>> on Mon, 15 May 2017 13:14:34 +0200 writes:
   >> > I see in the archives that the attachment cannot pass.
   >> > So, here is the code:
   >>
   >> [... MM: I needed to reformat etc to match closely to
   >> the current source code which is in
   >> https://svn.r-project.org/R/trunk/src/library/base/R/stop.R
   >> or its corresponding github mirror
   >> https://github.com/wch/r-source/blob/trunk/src/library/base/R/stop.R
   >> ]
   >>
   >> > Best,
   >> > Serguei.
   >>
   >> Yes, something like that seems even simpler than Peter's
   >> suggestion...
   >>
   >> It currently breaks 'make check' in the R sources,
   >> specifically in tests/reg-tests-2.R (lines 6574 ff),
   >> the new code now gives
   >>
   >> > ## error messages from (C-level) evalList
   >> > tst <- function(y) { stopifnot(is.numeric(y)); y+ 1 }
   >> > try(tst())
   >> Error in eval(cl.i, pfr) : argument "y" is missing, with no default
   >>
   >> whereas previously it gave
   >>
   >> Error in stopifnot(is.numeric(y)) :
   >> argument "y" is missing, with no default
   >>
   >>
   >> But I think that change (of call stack in such an error case) is
   >> unavoidable and not a big problem.

   > It can be avoided but at price of customizing error() and warning() calls 
with something like:
   > wrn <- function(w) {w$call <- cl.i; warning(w)}
   > err <- function(e) {e$call <- cl.i; stop(e)}
   > ...
   > tryCatch(r <- eval(cl.i, pfr), warning=wrn, error=err)

   > Serguei.

Well, a good idea, but the 'warning' case is more complicated
(and the above incorrect): I do want the warning there, but
_not_ return the warning, but rather, the result of eval() :
So this needs even more sophistication, using  withCallingHandlers(.)
and maybe that really get's too sophisticated and no
more "readable" to 99.9% of the R users ... ?

I now do append my current version -- in case some may want to
comment or improve further.

Martin




--
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa  Phone: 319-335-3386
Department of Statistics andFax:   319-335-3017
   Actuarial Science
241 Schaeffer Hall  email:   luke-tier...@uiowa.edu
Iowa City, IA 52242 WWW:  http://www.stat.uiowa.edu
__
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Re: [Rd] stopifnot() does not stop at first non-TRUE argument

[Serguei Sokol]

Le 15/05/2017 à 17:44, Martin Maechler a écrit :
...

So this needs even more sophistication, using withCallingHandlers(.)
and maybe that really get's too sophisticated and no
more "readable" to 99.9% of the R users ... ?

I'd say the current version is of minimal sophistication to reach
both the doc and test requirements.

Serguei.

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

[Martin Maechler]

> Serguei Sokol 
> on Mon, 15 May 2017 16:32:20 +0200 writes:

> Le 15/05/2017 à 15:37, Martin Maechler a écrit :
>>> Serguei Sokol 
>>> on Mon, 15 May 2017 13:14:34 +0200 writes:
>> > I see in the archives that the attachment cannot pass.
>> > So, here is the code:
>> 
>> [... MM: I needed to reformat etc to match closely to
>> the current source code which is in
>> https://svn.r-project.org/R/trunk/src/library/base/R/stop.R
>> or its corresponding github mirror
>> https://github.com/wch/r-source/blob/trunk/src/library/base/R/stop.R
>> ]
>> 
>> > Best,
>> > Serguei.
>> 
>> Yes, something like that seems even simpler than Peter's
>> suggestion...
>> 
>> It currently breaks 'make check' in the R sources,
>> specifically in tests/reg-tests-2.R (lines 6574 ff),
>> the new code now gives
>> 
>> > ## error messages from (C-level) evalList
>> > tst <- function(y) { stopifnot(is.numeric(y)); y+ 1 }
>> > try(tst())
>> Error in eval(cl.i, pfr) : argument "y" is missing, with no default
>> 
>> whereas previously it gave
>> 
>> Error in stopifnot(is.numeric(y)) :
>> argument "y" is missing, with no default
>> 
>> 
>> But I think that change (of call stack in such an error case) is
>> unavoidable and not a big problem.

> It can be avoided but at price of customizing error() and warning() calls 
with something like:
> wrn <- function(w) {w$call <- cl.i; warning(w)}
> err <- function(e) {e$call <- cl.i; stop(e)}
> ...
> tryCatch(r <- eval(cl.i, pfr), warning=wrn, error=err)

> Serguei.

Well, a good idea, but the 'warning' case is more complicated
(and the above incorrect): I do want the warning there, but
_not_ return the warning, but rather, the result of eval() :
So this needs even more sophistication, using  withCallingHandlers(.)
and maybe that really get's too sophisticated and no
more "readable" to 99.9% of the R users ... ?

I now do append my current version -- in case some may want to
comment or improve further.

Martin

stopifnot <- function(...)
{
penv <- parent.frame()
cl <- match.call(envir = penv)[-1]
Dparse <- function(call, cutoff = 60L) {
ch <- deparse(call, width.cutoff = cutoff)
if(length(ch) > 1L) paste(ch[1L], "") else ch
}
head <- function(x, n = 6L) ## basically utils:::head.default()
x[seq_len(if(n < 0L) max(length(x) + n, 0L) else min(n, length(x)))]
abbrev <- function(ae, n = 3L)
paste(c(head(ae, n), if(length(ae) > n) ""), collapse="\n  ")
benv <- baseenv()
for (i in seq_along(cl)) {
cl.i <- cl[[i]]
## r <- eval(cl.i, envir = penv, enclos = benv)
##   but with correct warn/err messages:
r <- withCallingHandlers(
tryCatch(eval(cl.i, envir = penv, enclos = benv),
 error = function(e) { e$call <- cl.i; stop(e) }),
warning = function(w) { w$call <- cl.i; w })
if (!(is.logical(r) && !anyNA(r) && all(r))) {
msg <- ## special case for decently written 'all.equal(*)':
if(is.call(cl.i) && identical(cl.i[[1]], quote(all.equal)) &&
   (is.null(ni <- names(cl.i)) || length(cl.i) == 3L ||
length(cl.i <- cl.i[!nzchar(ni)]) == 3L))

sprintf(gettext("%s and %s are not equal:\n  %s"),
Dparse(cl.i[[2]]),
Dparse(cl.i[[3]]), abbrev(r))
else
sprintf(ngettext(length(r),
 "%s is not TRUE",
 "%s are not all TRUE"),
Dparse(cl.i))

stop(msg, call. = FALSE, domain = NA)
}
}
invisible()
}
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Re: [Rd] stopifnot() does not stop at first non-TRUE argument

[peter dalgaard]

However, it doesn't look much of a hassle to fuse my suggestion into the 
current stopifnot: Basically, just use eval(as.name(paste0("..",i))) instead of 
ll[[i]] and base the initial calculation of n on match.call() rather than on 
list(...).

-pd


> On 15 May 2017, at 17:04 , Martin Maechler  wrote:
> 
>> peter dalgaard 
>>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  
>>> 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@cbs.dk  Priv: pda...@gmail.com
> 
> 
> 
> 
> 
> 
> 
> 

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

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

[Martin Maechler]

> peter dalgaard 
> 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  
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@cbs.dk  Priv: pda...@gmail.com

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

[Serguei Sokol]

Le 15/05/2017 à 15:37, Martin Maechler a écrit :

Serguei Sokol 
 on Mon, 15 May 2017 13:14:34 +0200 writes:

 > I see in the archives that the attachment cannot pass.
 > So, here is the code:

 [... MM: I needed to reformat etc to match closely to
  the current source code which is in
 https://svn.r-project.org/R/trunk/src/library/base/R/stop.R
  or its corresponding github mirror
 https://github.com/wch/r-source/blob/trunk/src/library/base/R/stop.R
 ]

 > Best,
 > Serguei.

Yes, something like that seems even simpler than Peter's
suggestion...

It currently breaks 'make check' in the R sources,
specifically in tests/reg-tests-2.R (lines 6574 ff),
the new code now gives

   > ## error messages from (C-level) evalList
   > tst <- function(y) { stopifnot(is.numeric(y)); y+ 1 }
   > try(tst())
   Error in eval(cl.i, pfr) : argument "y" is missing, with no default

whereas previously it gave

   Error in stopifnot(is.numeric(y)) :
  argument "y" is missing, with no default


But I think that change (of call stack in such an error case) is
unavoidable and not a big problem.

It can be avoided but at price of customizing error() and warning() calls with 
something like:
wrn <- function(w) {w$call <- cl.i; warning(w)}
err <- function(e) {e$call <- cl.i; stop(e)}
...
tryCatch(r <- eval(cl.i, pfr), warning=wrn, error=err)

Serguei.



--

I'm still curious about Hervé's idea on using  switch()  for the
issue.

Martin


 > Le 15/05/2017 à 12:48, Serguei Sokol a écrit :
 >> Hello,
 >>
 >> I am a new on this list, so I introduce myself very briefly:
 >> my background is applied mathematics, more precisely scientific calculus
 >> applied for modeling metabolic systems, I am author/maintainer of
 >> few packages (Deriv, rmumps, arrApply).
 >>
 >> Now, on the subject of this discussion, I must say that I don't really 
understand
 >> Peter's argument:
 >>
 >> >>> To do it differently, you would have to do something like
 >> >>>
 >> >>> dots <- match.call(expand.dots=FALSE)$...
 >> >>>
 >> >>> and then explicitly evaluate each argument in turn in the caller
 >> >>> frame. This amount of nonstandard evaluation sounds like it would
 >> >>> incur a performance penalty, which could be undesirable.
 >> The first line of the current stopifnot()
 >> n <- length(ll <- list(...))
 >> already evaluates _all_ of the arguments
 >> in the caller frame. So to do the same only
 >> on a part of them (till the first FALSE or NA occurs)
 >> cannot be more penalizing than the current version, right?
 >>
 >> I attach here a slightly modified version called stopifnot_new()
 >> which works in accordance with the man page and
 >> where there are only two additional calls: parent.frame() and eval().
 >> I don't think it can be considered as real performance penalty
 >> as the same or bigger amount of (implicit) evaluations was
 >> already done in the current version:
 >>
 >>> source("stopifnot_new.R")
 >>> stopifnot_new(3 == 5, as.integer(2^32), a <- 12)
 >> Error: 3 == 5 is not TRUE
 >>> a
 >> Error: object 'a' not found
 >>
 >> Best,
 >> Serguei.
 >>
 >>
 >> Le 15/05/2017 à 10:39, Martin Maechler a écrit :
  Hervé Pagès 
  on Wed, 3 May 2017 12:08:26 -0700 writes:
 >>> > On 05/03/2017 12:04 PM, Hervé Pagès wrote:
 >>> >> Not sure why the performance penalty of nonstandard evaluation would
 >>> >> be more of a concern here than for something like switch().
 >>>
 >>> > which is actually a primitive. So it seems that there is at least
 >>> > another way to go than 'dots <- match.call(expand.dots=FALSE)$...'
 >>>
 >>> > Thanks, H.
 >>>
 >>> >>
 >>> >> If that can't/won't be fixed, what about fixing the man page so it's
 >>> >> in sync with the current behavior?
 >>> >>
 >>> >> Thanks, H.
 >>>
 >>> Being back from vacations,...
 >>> I agree that something should be done here, if not to the code than at
 >>> least to the man page.
 >>>
 >>> For now, I'd like to look a bit longer into a possible change to the 
function.
 >>> Peter mentioned a NSE way to fix the problem and you mentioned 
switch().
 >>>
 >>> Originally, stopifnot() was only a few lines of code and meant to be
 >>> "self-explaining" by just reading its definition, and I really would 
like
 >>> to not walk too much away from that original idea.
 >>> How did you (Herve) think to use  switch()  here?
 >>>
 >>>
 >>>
 >>> >> On 05/03/2017 02:26 AM, peter dalgaard wrote:
 >>> >>> The first line of stopifnot is
 >>> >>>
 >>> >>> n <- length(ll <- list(...))
 >>> >>>
 >>> >>> which takes ALL arguments and forms a list of them. This implies
 >>> >>> 

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

[peter dalgaard]

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. 

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:

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  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@cbs.dk  Priv: pda...@gmail.com

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

[Martin Maechler]

> Serguei Sokol 
> on Mon, 15 May 2017 13:14:34 +0200 writes:

> I see in the archives that the attachment cannot pass.
> So, here is the code:

[... MM: I needed to reformat etc to match closely to
 the current source code which is in
 https://svn.r-project.org/R/trunk/src/library/base/R/stop.R
 or its corresponding github mirror
https://github.com/wch/r-source/blob/trunk/src/library/base/R/stop.R
]

> Best,
> Serguei.

Yes, something like that seems even simpler than Peter's
suggestion...

It currently breaks 'make check' in the R sources,
specifically in tests/reg-tests-2.R (lines 6574 ff),
the new code now gives

  > ## error messages from (C-level) evalList
  > tst <- function(y) { stopifnot(is.numeric(y)); y+ 1 }
  > try(tst())
  Error in eval(cl.i, pfr) : argument "y" is missing, with no default

whereas previously it gave

  Error in stopifnot(is.numeric(y)) : 
 argument "y" is missing, with no default


But I think that change (of call stack in such an error case) is
unavoidable and not a big problem.

--

I'm still curious about Hervé's idea on using  switch()  for the
issue.

Martin


> Le 15/05/2017 à 12:48, Serguei Sokol a écrit :
>> Hello,
>> 
>> I am a new on this list, so I introduce myself very briefly:
>> my background is applied mathematics, more precisely scientific calculus
>> applied for modeling metabolic systems, I am author/maintainer of
>> few packages (Deriv, rmumps, arrApply).
>> 
>> Now, on the subject of this discussion, I must say that I don't really 
understand
>> Peter's argument:
>> 
>> >>> To do it differently, you would have to do something like
>> >>>
>> >>> dots <- match.call(expand.dots=FALSE)$...
>> >>>
>> >>> and then explicitly evaluate each argument in turn in the caller
>> >>> frame. This amount of nonstandard evaluation sounds like it would
>> >>> incur a performance penalty, which could be undesirable.
>> The first line of the current stopifnot()
>> n <- length(ll <- list(...))
>> already evaluates _all_ of the arguments
>> in the caller frame. So to do the same only
>> on a part of them (till the first FALSE or NA occurs)
>> cannot be more penalizing than the current version, right?
>> 
>> I attach here a slightly modified version called stopifnot_new()
>> which works in accordance with the man page and
>> where there are only two additional calls: parent.frame() and eval().
>> I don't think it can be considered as real performance penalty
>> as the same or bigger amount of (implicit) evaluations was
>> already done in the current version:
>> 
>>> source("stopifnot_new.R")
>>> stopifnot_new(3 == 5, as.integer(2^32), a <- 12)
>> Error: 3 == 5 is not TRUE
>>> a
>> Error: object 'a' not found
>> 
>> Best,
>> Serguei.
>> 
>> 
>> Le 15/05/2017 à 10:39, Martin Maechler a écrit :
 Hervé Pagès 
 on Wed, 3 May 2017 12:08:26 -0700 writes:
>>> > On 05/03/2017 12:04 PM, Hervé Pagès wrote:
>>> >> Not sure why the performance penalty of nonstandard evaluation would
>>> >> be more of a concern here than for something like switch().
>>> 
>>> > which is actually a primitive. So it seems that there is at least
>>> > another way to go than 'dots <- match.call(expand.dots=FALSE)$...'
>>> 
>>> > Thanks, H.
>>> 
>>> >>
>>> >> If that can't/won't be fixed, what about fixing the man page so it's
>>> >> in sync with the current behavior?
>>> >>
>>> >> Thanks, H.
>>> 
>>> Being back from vacations,...
>>> I agree that something should be done here, if not to the code than at
>>> least to the man page.
>>> 
>>> For now, I'd like to look a bit longer into a possible change to the 
function.
>>> Peter mentioned a NSE way to fix the problem and you mentioned switch().
>>> 
>>> Originally, stopifnot() was only a few lines of code and meant to be
>>> "self-explaining" by just reading its definition, and I really would 
like
>>> to not walk too much away from that original idea.
>>> How did you (Herve) think to use  switch()  here?
>>> 
>>> 
>>> 
>>> >> On 05/03/2017 02:26 AM, peter dalgaard wrote:
>>> >>> The first line of stopifnot is
>>> >>>
>>> >>> n <- length(ll <- list(...))
>>> >>>
>>> >>> which takes ALL arguments and forms a list of them. This implies
>>> >>> evaluation, so explains the effect that you see.
>>> >>>
>>> >>> To do it differently, you would have to do something like
>>> >>>
>>> >>> dots <- match.call(expand.dots=FALSE)$...
>>> >>>
>>> >>> and then explicitly evaluate each argument in turn in the caller
>>> >>> frame. This amount of nonstandard evaluation sounds like it would
>>> >>> incur a 

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

[Serguei Sokol]

I see in the archives that the attachment cannot pass.
So, here is the code:
8<
stopifnot_new <- function (...)
{
mc <- match.call()
n <- length(mc)-1
if (n == 0L)
return(invisible())
Dparse <- function(call, cutoff = 60L) {
ch <- deparse(call, width.cutoff = cutoff)
if (length(ch) > 1L)
paste(ch[1L], "")
else ch
}
head <- function(x, n = 6L) x[seq_len(if (n < 0L) max(length(x) +
n, 0L) else min(n, length(x)))]
abbrev <- function(ae, n = 3L) paste(c(head(ae, n), if (length(ae) >
n) ""), collapse = "\n  ")
pfr <- parent.frame()
for (i in 1L:n) {
cl.i <- mc[[i + 1L]]
r <- eval(cl.i, pfr)
if (!(is.logical(r) && !anyNA(r) && all(r))) {
msg <- if (is.call(cl.i) && identical(cl.i[[1]], quote(all.equal)) 
&&
(is.null(ni <- names(cl.i)) || length(cl.i) == 3L ||
length(cl.i <- cl.i[!nzchar(ni)]) == 3L))
sprintf(gettext("%s and %s are not equal:\n  %s"),
Dparse(cl.i[[2]]), Dparse(cl.i[[3]]), abbrev(r))
else sprintf(ngettext(length(r), "%s is not TRUE", "%s are not all 
TRUE"),
Dparse(cl.i))
stop(msg, call. = FALSE, domain = NA)
}
}
invisible()
}
8<

Best,
Serguei.

Le 15/05/2017 à 12:48, Serguei Sokol a écrit :

Hello,

I am a new on this list, so I introduce myself very briefly:
my background is applied mathematics, more precisely scientific calculus
applied for modeling metabolic systems, I am author/maintainer of
few packages (Deriv, rmumps, arrApply).

Now, on the subject of this discussion, I must say that I don't really 
understand
Peter's argument:

>>> To do it differently, you would have to do something like
>>>
>>> dots <- match.call(expand.dots=FALSE)$...
>>>
>>> and then explicitly evaluate each argument in turn in the caller
>>> frame. This amount of nonstandard evaluation sounds like it would
>>> incur a performance penalty, which could be undesirable.
The first line of the current stopifnot()
n <- length(ll <- list(...))
already evaluates _all_ of the arguments
in the caller frame. So to do the same only
on a part of them (till the first FALSE or NA occurs)
cannot be more penalizing than the current version, right?

I attach here a slightly modified version called stopifnot_new()
which works in accordance with the man page and
where there are only two additional calls: parent.frame() and eval().
I don't think it can be considered as real performance penalty
as the same or bigger amount of (implicit) evaluations was
already done in the current version:


source("stopifnot_new.R")
stopifnot_new(3 == 5, as.integer(2^32), a <- 12)

Error: 3 == 5 is not TRUE

a

Error: object 'a' not found

Best,
Serguei.


Le 15/05/2017 à 10:39, Martin Maechler a écrit :

Hervé Pagès 
 on Wed, 3 May 2017 12:08:26 -0700 writes:

 > On 05/03/2017 12:04 PM, Hervé Pagès wrote:
 >> Not sure why the performance penalty of nonstandard evaluation would
 >> be more of a concern here than for something like switch().

 > which is actually a primitive. So it seems that there is at least
 > another way to go than 'dots <- match.call(expand.dots=FALSE)$...'

 > Thanks, H.

 >>
 >> If that can't/won't be fixed, what about fixing the man page so it's
 >> in sync with the current behavior?
 >>
 >> Thanks, H.

Being back from vacations,...
I agree that something should be done here, if not to the code than at
least to the man page.

For now, I'd like to look a bit longer into a possible change to the function.
Peter mentioned a NSE way to fix the problem and you mentioned switch().

Originally, stopifnot() was only a few lines of code and meant to be
"self-explaining" by just reading its definition, and I really would like
to not walk too much away from that original idea.
How did you (Herve) think to use  switch()  here?



 >> On 05/03/2017 02:26 AM, peter dalgaard wrote:
 >>> The first line of stopifnot is
 >>>
 >>> n <- length(ll <- list(...))
 >>>
 >>> which takes ALL arguments and forms a list of them. This implies
 >>> evaluation, so explains the effect that you see.
 >>>
 >>> To do it differently, you would have to do something like
 >>>
 >>> dots <- match.call(expand.dots=FALSE)$...
 >>>
 >>> and then explicitly evaluate each argument in turn in the caller
 >>> frame. This amount of nonstandard evaluation sounds like it would
 >>> incur a performance penalty, which could be undesirable.
 >>>
 >>> If you want to enforce the order of evaluation, there is always
 >>>
 >>> stopifnot(A) stopifnot(B)
 >>>
 >>> -pd
 >>>
  On 3 May 2017, at 02:50 , Hervé Pagès 
  wrote:
 
  Hi,
 
  It's surprising that stopifnot() 

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

[Serguei Sokol]

Hello,

I am a new on this list, so I introduce myself very briefly:
my background is applied mathematics, more precisely scientific calculus
applied for modeling metabolic systems, I am author/maintainer of
few packages (Deriv, rmumps, arrApply).

Now, on the subject of this discussion, I must say that I don't really 
understand
Peter's argument:

>>> To do it differently, you would have to do something like
>>>
>>> dots <- match.call(expand.dots=FALSE)$...
>>>
>>> and then explicitly evaluate each argument in turn in the caller
>>> frame. This amount of nonstandard evaluation sounds like it would
>>> incur a performance penalty, which could be undesirable.
The first line of the current stopifnot()
n <- length(ll <- list(...))
already evaluates _all_ of the arguments
in the caller frame. So to do the same only
on a part of them (till the first FALSE or NA occurs)
cannot be more penalizing than the current version, right?

I attach here a slightly modified version called stopifnot_new()
which works in accordance with the man page and
where there are only two additional calls: parent.frame() and eval().
I don't think it can be considered as real performance penalty
as the same or bigger amount of (implicit) evaluations was
already done in the current version:


source("stopifnot_new.R")
stopifnot_new(3 == 5, as.integer(2^32), a <- 12)

Error: 3 == 5 is not TRUE

a

Error: object 'a' not found

Best,
Serguei.


Le 15/05/2017 à 10:39, Martin Maechler a écrit :

Hervé Pagès 
 on Wed, 3 May 2017 12:08:26 -0700 writes:

 > On 05/03/2017 12:04 PM, Hervé Pagès wrote:
 >> Not sure why the performance penalty of nonstandard evaluation would
 >> be more of a concern here than for something like switch().

 > which is actually a primitive. So it seems that there is at least
 > another way to go than 'dots <- match.call(expand.dots=FALSE)$...'

 > Thanks, H.

 >>
 >> If that can't/won't be fixed, what about fixing the man page so it's
 >> in sync with the current behavior?
 >>
 >> Thanks, H.

Being back from vacations,...
I agree that something should be done here, if not to the code than at
least to the man page.

For now, I'd like to look a bit longer into a possible change to the function.
Peter mentioned a NSE way to fix the problem and you mentioned switch().

Originally, stopifnot() was only a few lines of code and meant to be
"self-explaining" by just reading its definition, and I really would like
to not walk too much away from that original idea.
How did you (Herve) think to use  switch()  here?



 >> On 05/03/2017 02:26 AM, peter dalgaard wrote:
 >>> The first line of stopifnot is
 >>>
 >>> n <- length(ll <- list(...))
 >>>
 >>> which takes ALL arguments and forms a list of them. This implies
 >>> evaluation, so explains the effect that you see.
 >>>
 >>> To do it differently, you would have to do something like
 >>>
 >>> dots <- match.call(expand.dots=FALSE)$...
 >>>
 >>> and then explicitly evaluate each argument in turn in the caller
 >>> frame. This amount of nonstandard evaluation sounds like it would
 >>> incur a performance penalty, which could be undesirable.
 >>>
 >>> If you want to enforce the order of evaluation, there is always
 >>>
 >>> stopifnot(A) stopifnot(B)
 >>>
 >>> -pd
 >>>
  On 3 May 2017, at 02:50 , Hervé Pagès 
  wrote:
 
  Hi,
 
  It's surprising that stopifnot() keeps evaluating its arguments
  after it reaches the first one that is not TRUE:
 
  > stopifnot(3 == 5, as.integer(2^32), a <- 12) Error: 3 == 5 is
  not TRUE In addition: Warning message: In stopifnot(3 == 5,
  as.integer(2^32), a <- 12) : NAs introduced by coercion to integer
  range > a [1] 12
 
  The details section in its man page actually suggests that it
  should stop at the first non-TRUE argument:
 
  ‘stopifnot(A, B)’ is conceptually equivalent to
 
  { if(any(is.na(A)) || !all(A)) stop(...); if(any(is.na(B)) ||
  !all(B)) stop(...) }
 
  Best, H.
 
  --
  Hervé Pagès
 
  Program in Computational Biology Division of Public Health
  Sciences Fred Hutchinson Cancer Research Center 1100 Fairview
  Ave. N, M1-B514 P.O. Box 19024 Seattle, WA 98109-1024
 
  E-mail: hpa...@fredhutch.org Phone: (206) 667-5791 Fax: (206)
  667-1319
 
  __
  R-devel@r-project.org mailing list
  

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

[Martin Maechler]

> Hervé Pagès 
> on Wed, 3 May 2017 12:08:26 -0700 writes:

> On 05/03/2017 12:04 PM, Hervé Pagès wrote:
>> Not sure why the performance penalty of nonstandard evaluation would
>> be more of a concern here than for something like switch().

> which is actually a primitive. So it seems that there is at least
> another way to go than 'dots <- match.call(expand.dots=FALSE)$...'

> Thanks, H.

>> 
>> If that can't/won't be fixed, what about fixing the man page so it's
>> in sync with the current behavior?
>> 
>> Thanks, H.

Being back from vacations,...
I agree that something should be done here, if not to the code than at
least to the man page.

For now, I'd like to look a bit longer into a possible change to the function.
Peter mentioned a NSE way to fix the problem and you mentioned switch().

Originally, stopifnot() was only a few lines of code and meant to be
"self-explaining" by just reading its definition, and I really would like
to not walk too much away from that original idea.
How did you (Herve) think to use  switch()  here?



>> On 05/03/2017 02:26 AM, peter dalgaard wrote:
>>> The first line of stopifnot is
>>> 
>>> n <- length(ll <- list(...))
>>> 
>>> which takes ALL arguments and forms a list of them. This implies
>>> evaluation, so explains the effect that you see.
>>> 
>>> To do it differently, you would have to do something like
>>> 
>>> dots <- match.call(expand.dots=FALSE)$...
>>> 
>>> and then explicitly evaluate each argument in turn in the caller
>>> frame. This amount of nonstandard evaluation sounds like it would
>>> incur a performance penalty, which could be undesirable.
>>> 
>>> If you want to enforce the order of evaluation, there is always
>>> 
>>> stopifnot(A) stopifnot(B)
>>> 
>>> -pd
>>> 
 On 3 May 2017, at 02:50 , Hervé Pagès 
 wrote:
 
 Hi,
 
 It's surprising that stopifnot() keeps evaluating its arguments
 after it reaches the first one that is not TRUE:
 
 > stopifnot(3 == 5, as.integer(2^32), a <- 12) Error: 3 == 5 is
 not TRUE In addition: Warning message: In stopifnot(3 == 5,
 as.integer(2^32), a <- 12) : NAs introduced by coercion to integer
 range > a [1] 12
 
 The details section in its man page actually suggests that it
 should stop at the first non-TRUE argument:
 
 ‘stopifnot(A, B)’ is conceptually equivalent to
 
 { if(any(is.na(A)) || !all(A)) stop(...); if(any(is.na(B)) ||
 !all(B)) stop(...) }
 
 Best, H.
 
 --
 Hervé Pagès
 
 Program in Computational Biology Division of Public Health
 Sciences Fred Hutchinson Cancer Research Center 1100 Fairview
 Ave. N, M1-B514 P.O. Box 19024 Seattle, WA 98109-1024
 
 E-mail: hpa...@fredhutch.org Phone: (206) 667-5791 Fax: (206)
 667-1319
 
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 R-devel@r-project.org mailing list
 
https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel=DwIFaQ=eRAMFD45gAfqt84VtBcfhQ=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA=JwgKhKD2k-9Kedeh6pqu-A8x6UEV0INrcxcSGVGo3Tg=f7IKJIhpRNJMC3rZAkuI6-MTdL3GAKSV2wK0boFN5HY=
 
>>> 
>> 

> -- Hervé Pagès

> Program in Computational Biology Division of Public Health Sciences
> Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N,
> M1-B514 P.O. Box 19024 Seattle, WA 98109-1024

> E-mail: hpa...@fredhutch.org Phone: (206) 667-5791 Fax: (206)
> 667-1319

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> https://stat.ethz.ch/mailman/listinfo/r-devel

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

[Hervé Pagès]

On 05/03/2017 12:04 PM, Hervé Pagès wrote:

Not sure why the performance penalty of nonstandard evaluation would
be more of a concern here than for something like switch().


which is actually a primitive. So it seems that there is at least
another way to go than 'dots <- match.call(expand.dots=FALSE)$...'

Thanks,
H.



If that can't/won't be fixed, what about fixing the man page so it's
in sync with the current behavior?

Thanks,
H.

On 05/03/2017 02:26 AM, peter dalgaard wrote:

The first line of stopifnot is

n <- length(ll <- list(...))

which takes ALL arguments and forms a list of them. This implies
evaluation, so explains the effect that you see.

To do it differently, you would have to do something like

   dots <- match.call(expand.dots=FALSE)$...

and then explicitly evaluate each argument in turn in the caller
frame. This amount of nonstandard evaluation sounds like it would
incur a performance penalty, which could be undesirable.

If you want to enforce the order of evaluation, there is always

   stopifnot(A)
   stopifnot(B)

-pd


On 3 May 2017, at 02:50 , Hervé Pagès  wrote:

Hi,

It's surprising that stopifnot() keeps evaluating its arguments after
it reaches the first one that is not TRUE:

 > stopifnot(3 == 5, as.integer(2^32), a <- 12)
 Error: 3 == 5 is not TRUE
 In addition: Warning message:
 In stopifnot(3 == 5, as.integer(2^32), a <- 12) :
   NAs introduced by coercion to integer range
 > a
 [1] 12

The details section in its man page actually suggests that it should
stop at the first non-TRUE argument:

 ‘stopifnot(A, B)’ is conceptually equivalent to

  { if(any(is.na(A)) || !all(A)) stop(...);
if(any(is.na(B)) || !all(B)) stop(...) }

Best,
H.

--
Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpa...@fredhutch.org
Phone:  (206) 667-5791
Fax:(206) 667-1319

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--
Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpa...@fredhutch.org
Phone:  (206) 667-5791
Fax:(206) 667-1319

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

[Hervé Pagès]

Not sure why the performance penalty of nonstandard evaluation would
be more of a concern here than for something like switch().

If that can't/won't be fixed, what about fixing the man page so it's
in sync with the current behavior?

Thanks,
H.

On 05/03/2017 02:26 AM, peter dalgaard wrote:

The first line of stopifnot is

n <- length(ll <- list(...))

which takes ALL arguments and forms a list of them. This implies evaluation, so 
explains the effect that you see.

To do it differently, you would have to do something like

   dots <- match.call(expand.dots=FALSE)$...

and then explicitly evaluate each argument in turn in the caller frame. This 
amount of nonstandard evaluation sounds like it would incur a performance 
penalty, which could be undesirable.

If you want to enforce the order of evaluation, there is always

   stopifnot(A)
   stopifnot(B)

-pd


On 3 May 2017, at 02:50 , Hervé Pagès  wrote:

Hi,

It's surprising that stopifnot() keeps evaluating its arguments after
it reaches the first one that is not TRUE:

 > stopifnot(3 == 5, as.integer(2^32), a <- 12)
 Error: 3 == 5 is not TRUE
 In addition: Warning message:
 In stopifnot(3 == 5, as.integer(2^32), a <- 12) :
   NAs introduced by coercion to integer range
 > a
 [1] 12

The details section in its man page actually suggests that it should
stop at the first non-TRUE argument:

 ‘stopifnot(A, B)’ is conceptually equivalent to

  { if(any(is.na(A)) || !all(A)) stop(...);
if(any(is.na(B)) || !all(B)) stop(...) }

Best,
H.

--
Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpa...@fredhutch.org
Phone:  (206) 667-5791
Fax:(206) 667-1319

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--
Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpa...@fredhutch.org
Phone:  (206) 667-5791
Fax:(206) 667-1319

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