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

[Marius Hofert]

>
> if (requireNamespace("bar", quietly = TRUE)) {
>    # do the good stuff
> } else {
>    # do some less good substitute
> }
>
> without generating an error anywhere.

Hi Duncan,

thanks for helping.

I use the above

>
>
>>
>> '::' or ':::' import not declared from: ‘bar’
>> 'loadNamespace' or 'requireNamespace' call not declared from: ‘bar’
>
> Right, you shouldn't refer to a package in code without mentioning it in
> the DESCRIPTION file.

This is my problem. It seems that even a *conditional* use already
requires the package name to appear in DESCRIPTION. 'bar' was in
Imports and I tried to submit 'foo' with 'bar' in Suggests. Both times
was not accepted. I don't see how even a conditional use of 'bar'
inside 'foo' is possible then.

Cheers,
Marius

>
>>
>> Does this mean it is not possible to use 'bar' anymore in 'foo'?
>
> I don't think so.  But CRAN policies may have changed...
>
> Duncan Murdoch
>
>>
>> These are (somewhat) related references I found:
>> 1) https://cran.r-project.org/doc/manuals/r-release/R-exts.html#Suggested-packages
>> 2) https://stat.ethz.ch/pipermail/r-devel/2013-February/065947.html
>>
>
>