[Rd] R CMD check for the R code from vignettes

[Yihui Xie]

Yes, I completely agree the tangle code should run without errors, if
the package author has provided such a script. However, I think it is
also the package author's right to choose not to provide such a
script, for reasons that I stated in the beginning (1. redundancy; 2.
tangle functions ignore inline expressions that should not be
ignored).

It seems that I still need to clarify it: I'm not talking about
disabling _running_ the tangled code, but disabling _generating_ the
code _optionally_. Unless someone is arguing that the tangled code
_must_ be generated from vignettes, I do not think anybody in this
discussion really has a conflict with anybody else.

Please also note that I do not expect R core or CRAN maintainers to do
any extra work: package authors can easily disable tangle by
themselves without anything special flags to R CMD build or R CMD
check. The vignettes are still built normally (in terms of "weave"). I
brought forward the discussion to hear the possible harm that I was
potentially not aware of when we disable tangle for R package
vignettes (e.g. does it affect the quality of the package?). So far I
have not heard real harm (I admit my judgment is subjective).

Regards,
Yihui
--
Yihui Xie <xieyihui at gmail.com>
Web: http://yihui.name


On Mon, Jun 2, 2014 at 10:19 AM, Paul Gilbert <pgilbert902 at gmail.com> wrote:
>
>
> On 06/02/2014 12:16 AM, Gabriel Becker wrote:
>>
>> Carl,
>>
>> I don't really have a horse in this race other than a strong feeling that
>> whatever check does should be mandatory.
>>
>> That having been said, I think it can be argued that the fact that check
>> does this means that it IS in the R package vignette specification that
>> all
>> vignettes must be such that their tangled code will run without errors.
>
>
> My understanding of this is that the package maintainer can turn off
> building the vignette (--no-vignettes) but R CMD check and CRAN still check
> that the tangle code runs, and the check fails if it does not. Running the
> tangle code can be turned off, just not by the package maintainer. You have
> to make a special appeal to the CRAN maintainers, and give reasons they are
> prepared to accept. I think the intention is that the tangle code should run
> without errors. I doubt they would accept "it doesn't work" as an acceptable
> reason. But there are reasons, like the vignette requires access to a
> commercial database engine. Also, I think, turning this off means they just
> do not run it regularly, in the daily checks. I don't think it necessarily
> means the code is never tested. The testing may need to be done on machines
> with special resources.
>
> Thus, --no-vignettes provides a mechanism to avoid running the tangle code
> twice but, without special exemption, it is still run once. Some package
> maintainers may not think of several feature of 'R CMD check' as 'aids'. I
> think of it having more to do with maintaining some quality assurance, which
> I think of as an aid but not a debugging aid.
>
> I believe the CRAN maintainers have intentionally, and successfully, made
> disabling the running of tangled code  more trouble than it is generally
> worth. Effectively, a package should have tangle code that runs without
> errors.
>
> (Of course, I could be wrong about all this, it has happened before.)
>
> Paul