[R-pkg-devel] if statements in NAMESPACE file

[Duncan Murdoch]

On 30/09/2021 5:21 p.m., Jeff Newmiller wrote:
> What if you are on Windows but running R at the command prompt, or via cygwin, or in the console window of RStudio?
> 
> This seems unstable to me.

Sorry, too much context missing.  What's unstable?

Duncan Murdoch

> 
> On September 30, 2021 11:52:16 AM PDT, Andrew Simmons <akwsimmo using gmail.com> wrote:
>> Hello,
>>
>>
>> I'm updating my package 'this.path' which is supposed to retrieve the
>> absolute path of the executing script when called. It's similar to 'here',
>> except that 'here' constructs paths relative to a project directory,
>> whereas 'this.path' constructs paths relative to script directories. I was
>> updating the section where I retrieve the executing script's path while
>> running from a script open in Rgui for Windows, and I needed
>> utils::getWindowsHandles to do such a thing. But utils::getWindowsHandles
>> is a Windows only function, I
>> would imagine that 'utils' contains a similar line of code as above:
>>
>>
>> if (.Platform$OS.type == "windows")
>>     getWindowsHandles <- function() ...
>>
>>
>> and then in the NAMESPACE:
>>
>>
>> if (.Platform$OS.type == "windows")
>>     export(getWindowsHandles)
>>
>>
>> so I'd like to change my code to getWindowsHandles and import
>> getWindowsHandles from utils, but I can only do that on Windows, and so the
>> conditional importing should work for me. At no point does my function
>> mis-behave because of a attempting to use a function that isn't exported on
>> that platform, because within the function it only uses getWindowsHandles
>> if the OS is Windows.
>>
>>
>> On Thu, Sep 30, 2021 at 11:01 AM Mark Miller <mark.roman.miller using gmail.com>
>> wrote:
>>
>>> Returning to the original question, if it's helpful: I'd like to know what
>>> constraints led to considering an export only available on Windows, and see
>>> if we can suggest some other designs. It'd be good to keep the user's
>>> mental model abstracted from the platform they're working on. There are
>>> often unavoidable differences due to platform, but usually they're handled
>>> with warnings and errors rather than selective exports.
>>>
>>> On Thu, Sep 30, 2021 at 3:40 AM Berry Boessenkool <
>>> berryboessenkool using hotmail.com> wrote:
>>>
>>>>
>>>> One of the very best fortunes nominations!
>>>>
>>>> [...]
>>>>
>>>>    I suspect something like
>>>>
>>>>     if (stats::runif(1) > 0.5) export(someFunction)
>>>>
>>>> would work too, for a particularly frustrating experience for your
>>>> users.  It would mean half the installs export the function, and half
>>>> don't.
>>>>
>>>> Duncan Murdoch
>>>>
>>>>
>>>>          [[alternative HTML version deleted]]
>>>>
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>>>
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>>>
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>>
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>>
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