>>>>> Henrik Bengtsson
>>>>> on Thu, 20 Mar 2025 11:55:05 -0700 writes:
>> I'm pretty convinced we should fix it by checking for
>> primitive functions inside the C code of `attributes<-` :
>> arguably the bug is really there, rather than in
>> structure().
>>
>> Patches are welcome (via R's Bugzilla or just here).
> Thank you Martin. I'll make sure I create a brief BugZilla
> report on this, and hopefully a follow with a patch later
> on.
> One question on urgency or not: Is it too late to get such
> a change in for the R 4.5.0 release? I suspect so, because
> it has a potential of breaking existing packages. But if
> there's a possibility of fixing this in R 4.5.0, I'll make
> this a top priority. Please let me know.
> /Henrik
In such cases, I always go to https://developer.r-project.org/
and look at the release schedule.
Important for this Q seems
* Friday 2025-03-14: GRAND-FEATURE FREEZE (4.5.0 alpha)
* Friday 2025-03-28: FEATURE FREEZE (4.5.0 beta)
* Friday 2025-04-04: CODE FREEZE (4.5.0 RC)
So, yes there's a possibility ... but as you mentioned, too,
it depends quite a bit on if the fix is easily affectiong useR
and CRAN/Bioc package space.
Martin
> On Thu, Mar 20, 2025 at 3:31 AM Martin Maechler
> <maech...@stat.math.ethz.ch> wrote:
>>
>> >>>>> Henrik Bengtsson >>>>> on Wed, 19 Mar 2025 10:58:46
>> -0700 writes:
>>
>> > Hello. > I just (re-)discovered that structure(sum,
>> init = 100) is "sticky", > i.e. it stays with
>> base::sum(). Here's an minimal example:
>>
>> > $ R --vanilla --quiet >> void <- structure(sum,
>> some_attr = TRUE) >> str(sum) > function (..., na.rm =
>> FALSE) > - attr(*, "some_attr")= logi TRUE
>>
>> >> From my very basic troubleshooting, it looks like this
>> is happening > for primitive functions. I think I
>> understand that this comes down to > primitive functions
>> cannot be copied and baseenv() being special, i.e. > in
>> structure() there will be no copy made of the primitive
>> function, > and then attributes()<- ends up modifying the
>> original primitive > function. Even if this is a
>> documented feature, I believe, it is a > silent feature
>> with risky side effects. We might already have code out >
>> there that silently produces incorrect results, because
>> of this > behavior. For example, I was about to a custom
>> reduce() function where > I control the initial value via
>> an "init" attribute of the reducer > function, e.g.
>>
>> > x <- 1:10 > sum1 <- reduce(x, `+`) > sum2 <- reduce(x,
>> structure(`+`, init = 100)) # == 100 + sum1
>>
>> > If I then call:
>>
>> > sum3 <- reduce(x, `+`)
>>
>> > the 'init' attribute that was set in the sum2 statement
>> will affect > sum3 such that sum3 == sum2, not sum3 ==
>> sum1 as one would expect.
>>
>>
>> > SUGGESTIONS:
>>
>> > If this is a bug, then I think it needs to be fixed. If
>> it cannot be > fixed, maybe this could be protected
>> against, e.g.
>>
>> >> void <- structure(sum, some_attr = TRUE) > Error: You
>> must not set attributes on a primitive function: sum
>>
>> > Maybe it's sufficient to implement a protection against
>> this in > attr()<-, attributes()<-, and class()<-.
>>
>> > Comments?
>>
>> > /Henrik
>>
>> Yes, this is a bug -- a version of your code above:
>>
>> > void <- structure(sum, foo = TRUE) > identical(void,
>> sum) [1] TRUE > sum function (..., na.rm = FALSE)
>> .Primitive("sum") attr(,"foo") [1] TRUE
>> >
>>
>> Above, you are already looking at ways to deal with it;
>> and that *is* more delicate, indeed:
>>
>> One thing we (R core) found previously (a couple of years
>> ago) was that the `structure(..)` function was already
>> too "slow" for it to be used in some base R functions,
>> and adding another if(..) to it will not help making it
>> faster ...
>>
>> OTOH, structure() being a pure R function (no direct
>> .Internal(), .Call() ..) is also important I think, as
>> it keeps its code nicely self documenting.
>>
>> I'm pretty convinced we should fix it by checking for
>> primitive functions inside the C code of `attributes<-` :
>> arguably the bug is really there, rather than in
>> structure().
>>
>> Patches are welcome (via R's Bugzilla or just here).
>>
>> Martin
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