t1-t2 only gains difftime class optionally

[MichaelChirico]

For #7229 / follow-up to #7213 -- in the next release, don't "award" the difftime class, but make that available.

[github-actions]

• HEAD=diff-date-compat stopped early for DT[,.SD] improved in #4501
• HEAD=diff-date-compat slower P<0.001 for memrecycle regression fixed in #5463
  

Generated via commit ec3f850

Download link for the artifact containing the test results: ↓ atime-results.zip

Task	Duration
R setup and installing dependencies	5 minutes and 18 seconds
Installing different package versions	11 minutes and 34 seconds
Running and plotting the test cases	4 minutes and 14 seconds

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.02%. Comparing base (11a9435) to head (ec3f850).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7237   +/-   ##
=======================================
  Coverage   99.02%   99.02%           
=======================================
  Files          87       87           
  Lines       16803    16804    +1     
=======================================
+ Hits        16640    16641    +1     
  Misses        163      163           

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[jangorecki]

Make sense to mention this option is only for temporary transition and should be generally avoided in favor of adapting code to the change

[tdhock]

"you can activate the new behavior by setting ..." is confusing to me. Isn't the default for this option to not be set, so it gets value NULL, which means the code will set the class/units attributes? In that case the new behavior is already activated and you would have to deactivate it if you want by setting the option TRUE, right?

[MichaelChirico]

it defaults to TRUE (in .onLoad)

…

On Wed, Aug 27, 2025, 6:44 AM Toby Dylan Hocking ***@***.***> wrote: ***@***.**** commented on this pull request. ------------------------------ In NEWS.md <#7237 (comment)> : > @@ -8,6 +8,8 @@ 1. `data.table(x=1, <expr>)`, where `<expr>` is an expression resulting in a 1-column matrix without column names, will eventually have names `x` and `V2`, not `x` and `V1`, consistent with `data.table(x=1, <expr>)` where `<expr>` results in an atomic vector, for example `data.table(x=1, cbind(1))` and `data.table(x=1, 1)` will both have columns named `x` and `V2`. In this release, the matrix case continues to be named `V1`, but the new behavior can be activated by setting `options(datatable.old.matrix.autoname)` to `FALSE`. See point 5 under Bug Fixes for more context; this change will provide more internal consistency as well as more consistency with `data.frame()`. +2. `t1 - t2`, where both `t1` and `t2` are `IDate`, will eventually have class `difftime`, consistent with the case where `t1` and `t2` are both `Date`. You can activate the new behavior by setting `options(datatable.old.diff.time = FALSE)`. See point 17 under Bug Fixes for more context. "you can activate the new behavior by setting ..." is confusing to me. Isn't the default for this option to not be set, so it gets value NULL, which means the code will set the class/units attributes? In that case the new behavior is already activated and you would have to deactivate it if you want by setting the option TRUE, right? — Reply to this email directly, view it on GitHub <#7237 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB2BA5IT6TJZ7S5LKTRNCX33PWY2VAVCNFSM6AAAAACDISE5O2VHI2DSMVQWIX3LMV43YUDVNRWFEZLROVSXG5CSMV3GSZLXHMZTCNJZHA3DEOBUHA> . You are receiving this because you authored the thread.Message ID: ***@***.***>