[Rd] Undocumented change of dirname("C:/") on R-devel on Windows

[Hiroaki Yutani]

I confirmed the revert fixed my failing test. Thanks!

2023年2月23日(木) 20:12 Hiroaki Yutani <yutani.ini using gmail.com>:

> Thanks for the prompt response, I'll confirm it after the new R-devel
> binary is available.
> Also, thanks for the detailed explanation. I agree with you in general.
>
> > "/" in "C:/" is a path separator or not, and whether it is trailing or
> not
>
> It seems a Windows' path basically consists of two components; a drive
> specification (e.g., C:) and the directory structure within the drive. What
> I learned today is that both "C:/" and "C:" are valid path specifications,
> but refer to different locations; "C:" is not the root directory of the
> drive, but just a relative path [1]. So, I agree with you that the basename
> of "C:/" should be "C:/". However, at the same time, I don't feel this is
> worth a breaking change, so I think we can preserve the current (R 4.2.2)
> behavior.
>
> [1]:
> https://learn.microsoft.com/en-us/dotnet/standard/io/file-path-formats#apply-the-current-directory
>
> Best,
> Yutani
>
> 2023年2月23日(木) 17:15 Tomas Kalibera <tomas.kalibera using gmail.com>:
>
>>
>> On 2/23/23 03:27, Hiroaki Yutani wrote:
>> > Hi,
>> >
>> > I found dirname() behaves differently on R-devel on Windows. Since I'm
>> not
>> > sure which behavior is right, let me ask here before filing this to R's
>> > Bigzilla.
>> >
>> > On R 4.2.2., we get
>> >
>> >      > dirname("C:/")
>> >      [1] "C:/"
>> >
>> > However, on R-devel (r83888), we get
>> >
>> >      > dirname("C:/")
>> >      [1] "."
>> >
>> > ?dirname says 'dirname returns the part of the path up to but excluding
>> the
>> > last path separator, or "." if there is no path separator,' but I don't
>> see
>> > how the root path is supposed to be treated based on this rule (,
>> whether
>> > it's WIndows or UNIX-alike).
>> Thanks for spotting the difference, I've reverted to the previous
>> behavior, the change was unintentional. If you spot any other suspicious
>> changes in behavior in file-system operations, please report.
>> > What should we expect as the return value of dirname("C:/")? I feel the
>> > current behavior on R 4.2.2 is right, but I'd like to confirm.
>>
>> I also think the old behavior is better, even though it could be argued
>> whether the "/" in "C:/" is a path separator or not, and whether it is
>> trailing or not. But the behavior is in line with Unix where dirname of
>> "/" is also "/". Msys2 would return "C:".
>>
>> If  "/" in "C:/" is a path separator but not a trailing path separator,
>> then basename("C:/") should probably be "" and not "C:", and this would
>> be in line with what R does on Unix. However, to be in line with Unix, I
>> think the basename of "C:/" should be "C:/". Yet, Msys2 returns "C:"
>> which is what R does now.
>>
>> So what these functions should do on Windows is definitely tricky. In
>> either case the behavior is now again as in R 4.2.2.
>>
>> Best
>> Tomas
>>
>> >
>> > Best,
>> > Yutani
>> >
>> >       [[alternative HTML version deleted]]
>> >
>> > ______________________________________________
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>> > https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>

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