Herv? Pag?s <hpages at fredhutch.org>
on Wed, 3 May 2017 12:08:26 -0700 writes:
> On 05/03/2017 12:04 PM, Herv? Pag?s 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)$...'
>>
>> If that can't/won't be fixed, what about fixing the man page so it's
>> in sync with the current behavior?
>>
>> Thanks, H.
Being back from vacations,...
I agree that something should be done here, if not to the code than at
least to the man page.
For now, I'd like to look a bit longer into a possible change to the function.
Peter mentioned a NSE way to fix the problem and you mentioned switch().
Originally, stopifnot() was only a few lines of code and meant to be
"self-explaining" by just reading its definition, and I really would like
to not walk too much away from that original idea.
How did you (Herve) think to use switch() here?
>> On 05/03/2017 02:26 AM, peter dalgaard wrote:
>>> The first line of stopifnot is
>>>
>>> n <- length(ll <- list(...))
>>>
>>> which takes ALL arguments and forms a list of them. This implies
>>> evaluation, so explains the effect that you see.
>>>
>>> To do it differently, you would have to do something like
>>>
>>> dots <- match.call(expand.dots=FALSE)$...
>>>
>>> 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 , 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
>>>>
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>>>>
> 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