[Rd] Should `as.difftime()` convert integer input to double?

[Kurt Hornik]

>>>>> Bill Dunlap writes:

Thanks: fixed now in the trunk with c82716.

Best
-k

> Forcing difftime's payload to be numeric would avoid anomalies like
>> as.difftime(123456789L, units="secs") * 100L
> Time difference of NA secs
> Warning message:
> In e2 * unclass(e1) : NAs produced by integer overflow
>> as.difftime(123456789, units="secs") * 100L
> Time difference of 12345678900 secs

> Note that there are packages (e.g., fst, a serialization package) which can
> (in C++ code) understand and create difftimes with integer payloads, so you
> may have trouble completely getting rid of such things.

> -Bill

> On Tue, Aug 9, 2022 at 11:26 AM Davis Vaughan <davis using rstudio.com> wrote:

>> Hi all,
>> 
>> Currently, `as.difftime()` with an integer input will produce a difftime
>> object that internally is built on an integer vector, i.e.:
>> 
>> x <- as.difftime(1L, units = "secs")
>> typeof(x)
>> #> [1] "integer"
>> 
>> x <- as.difftime(1, units = "secs")
>> typeof(x)
>> #> [1] "double"
>> 
>> I feel like difftime objects should always be built on *double* vectors.
>> There are a few reasons I feel like this should be true:
>> 
>> - There is an `as.double.difftime()` method, but no `as.integer.difftime()`
>> method, which implies something about what the underlying storage type is
>> assumed to be.
>> 
>> - AFAIK, there is no other way to produce a difftime object with integer
>> storage using the exposed API (aside from abusing the internal .difftime()
>> helper). Even `.Date(1L) - .Date(1L)` produces a difftime with double
>> storage.
>> 
>> - `seq.Date()` used to be able to produce dates with integer storage, but
>> as of recently even that edge case has been altered to always produce dates
>> with double storage. So a change to also force difftime to have double
>> storage would feel consistent with that.
>> 
>> https://github.com/wch/r-source/commit/0762ee983813c4df9b93f6b5ee52c910dcd3ab39
>> 
>> It looks like a patch to `as.difftime()` would be fairly straightforward
>> (i.e. ensuring that integer input is coerced to double), so I'd be happy to
>> attempt one if someone else agrees that this should be changed.
>> 
>> Thanks,
>> Davis
>> 
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>> 
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