[R-pkg-devel] How to (conditionally) use an archived package (without Suggests)?

[Duncan Murdoch]

On 24/02/2018 7:56 PM, Marius Hofert wrote:
> On Sun, Feb 25, 2018 at 1:41 AM, Duncan Murdoch
> <murdoch.duncan at gmail.com> wrote:
>> On 24/02/2018 7:26 PM, Marius Hofert wrote:
>>> On Sun, Feb 25, 2018 at 1:09 AM, Dirk Eddelbuettel <edd at debian.org> wrote:
>>>>
>>>> On 25 February 2018 at 00:45, Marius Hofert wrote:
>>>> | A package 'foo' uses a package 'bar' (in Imports). 'bar' has been
>>>> | archived and the maintainer of 'foo' was asked to fix the dependency
>>>> | on 'bar' according to WRE 1.1.3.1.
>>>> |
>>>> | Working with 'bar::' everywhere (and requireNamespace("bar", quietly =
>>>> | TRUE)), as well as moving 'bar' from Imports to Suggests seems to work
>>>> | but is not accepted on submission. Removing 'bar' also from Suggests
>>>> | leads to
>>>> |
>>>> | '::' or ':::' import not declared from: ‘bar’
>>>> | 'loadNamespace' or 'requireNamespace' call not declared from: ‘bar’
>>>> |
>>>> | Does this mean it is not possible to use 'bar' anymore in 'foo'?
>>>>
>>>> Your title says "conditionally".
>>>>
>>>> Does your code actually behave conditionally, ie does foo check if bar is
>>>> available, and only use its code if it is?
>>>
>>> Hi Dirk,
>>>
>>> nice to hear from you and thanks for helping!
>>>
>>> Yes, 'foo' essentially has one main function with an argument 'method
>>> = c("b", "ba", "bar")'. If the user chooses to call the function with
>>> method = "bar", then it is checked whether "bar" is installed (as
>>> described in WRE) and an error is thrown if not.
>>
>> Don't throw an error, work around it.
> 
> Hi,
> 
> the 'workaround' is the error: to tell the user not to use it (but one
> of the other available methods).
> 
> To be more precise: 'bar' is the package 'loon' for dynamic graphics
> (and 'foo' is 'zenplots'). If that's not installed, the user can
> choose to work with the other (non-dynamic) graphics packages. If a
> user actively chooses to do the plotting with loon but doesn't have
> loon installed, the error is a logical consequence.
> 
>> If you have no alternative code,
>> then don't test the "bar" code unless "bar" is installed.
> 
> The main plotting function in zenplots uses:
> 
>      if(pkg == "loon" && !requireNamespace("loon", quietly = TRUE))
>          stop("Package 'loon' is not available.")
> 
> ... and if it's installed, it will call various further functions from
> loon (now all used via "loon::..."). There are no tests or examples
> that fail, everything works -- it's just that the use of "::"
> generates the warning I mentioned which is (most likely) unacceptable
> for upload to CRAN.
> 
>>
>> The basic idea is that your package should pass tests without errors
>> even if "bar" is not available.
> 
> It does -- except for the 'warning':
> 
> '::' or ':::' import not declared from: ‘bar’
> 'loadNamespace' or 'requireNamespace' call not declared from: ‘bar’

That's because 'bar' is not in Suggests.
> 
>>
>> I think Dirk is wrong saying that "bar" has to be available; CRAN isn't
>> going to go looking for it.  But they do want your package to pass all
>> tests even if none of the Suggests packages is available.
> 
> 'loon' is not in Suggests. It originally was in 'Imports', then I put
> it to 'Suggests', but when I submitted, Uwe wrote:
> 
> But you still have
> Suggests: loon,
> Please fix and resubmit >
> ... so it shouldn't appear in 'Suggests' either (I guess). That's why
> I also removed it from Suggests, but then (because of the above
> warning), I can't submit either.

I suspect you didn't run an --as-cran check with no 'loon' available, 
and if you had, you would have received warnings or errors.

If you did run that check and it didn't give warnings or errors, then 
things have changed; sorry for misleading you.

Duncan Murdoch

> 
> Not sure how to solve this (... and thought that others might have a
> similar problem with archived packages -- thus this post).
> 
> Cheers,
> Marius
> 
>>
>> Duncan Murdoch
>>
>>>
>>>>
>>>> One additional difficulty may be that even for Suggests, it still has to be
>>>> accessible "somewhere" .
>>>
>>> The full story is this: 'bar' has been archived because 'problems were
>>> not corrected despite reminders'. 'bar' is mainly developed on github
>>> and is probably easy to fix, but I also couldn't reach the maintainer
>>> and I thought it's better to 'decrease' the dependency on 'bar' as
>>> much as possible. 'bar' is actually quite intrusive to install/use
>>> (requires R to be configured with tcltk). However, 'bar' provides some
>>> nice features which the other methods ("b", "ba") don't have -- would
>>> be a pity to completely remove 'bar' from 'foo'.
>>>
>>> So 'bar' is on github (and thus could be installed from there + 'foo'
>>> could make use of 'bar' conditionally... just don't know how to submit
>>> 'foo' to CRAN because of the warning)
>>>
>>> Cheers,
>>> M
>>>
>>>
>>>
>>>> And "archived" is not.  You could just move bar
>>>> onto a drat repo you set yp -- we have done the same for data packages and
>>>> have a R Journal paper describing it:
>>>>
>>>>      https://journal.r-project.org/archive/2017/RJ-2017-026/index.html
>>>>
>>>> Hth, Dirk
>>>>
>>>> --
>>>> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
>>>
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>>