R devel - May 2017 - stopifnot() does not stop at first non-TRUE argument

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.

-- 
Herv? Pag?s

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: hpages at fredhutch.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319

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 , Herv? Pag?s <hpages at fredhutch.org>
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.
> 
> -- 
> Herv? Pag?s
> 
> 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: hpages at fredhutch.org
> Phone:  (206) 667-5791
> Fax:    (206) 667-1319
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
-- 
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

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 , Herv? Pag?s <hpages at fredhutch.org>
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.
>>
>> --
>> Herv? Pag?s
>>
>> 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: hpages at fredhutch.org
>> Phone:  (206) 667-5791
>> Fax:    (206) 667-1319
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>>
https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel&d=DwIFaQ&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=JwgKhKD2k-9Kedeh6pqu-A8x6UEV0INrcxcSGVGo3Tg&s=f7IKJIhpRNJMC3rZAkuI6-MTdL3GAKSV2wK0boFN5HY&e>
-- 
Herv? Pag?s

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: hpages at fredhutch.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319