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

Duncan Murdoch murdoch.duncan at gmail.com
Sun Feb 25 01:41:32 CET 2018

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
>> |
>> | 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.  If you have no alternative code, 
then don't test the "bar" code unless "bar" is installed.

The basic idea is that your package should pass tests without errors 
even if "bar" is not available.

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.

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 The full story is this: 'bar' has been archived because 'problems were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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