[R-pkg-devel] Printing examples conditionally on another package in Suggests

[Georgi Boshnakov]

Maybe  Martin Maechler's post in response to a similar question answers your question:

https://stat.ethz.ch/pipermail/r-package-devel/2018q2/002780.html   

In summary, wrap the code in:

  if (requireNamespace("MASS", quietly = TRUE)) withAutoprint({

  your code

  })


Georgi Boshnakov

-----Original Message-----
From: R-package-devel [mailto:r-package-devel-bounces using r-project.org] On Behalf Of Zhian Kamvar
Sent: 10 August 2018 12:26
To: Alexandre Courtiol
Cc: R-list Package Devel
Subject: Re: [R-pkg-devel] Printing examples conditionally on another package in Suggests

Thanks, but my use of print here is really a toy example, not necessarily
the end-goal. This strategy would fail if I were to attempt load a data set
from some_package or use any functions from some_package.

A more specific example of what I'm dealing with is here:
http://www.repidemicsconsortium.org/incidence/reference/get_counts.html#examples.
This is what the user would see if they were to use example(get_counts).

On Fri, Aug 10, 2018 at 12:14 PM Alexandre Courtiol <
alexandre.courtiol using gmail.com> wrote:

> Perhaps then something like:
> Print <- function(x) if (requireNamespace("some.package", quietly = TRUE))
> print(x)
> Print("Hi")
> Print("Hello")
> Print("Goodbye")
>
>
>
> On Fri, 10 Aug 2018 at 12:33, Zhian Kamvar <zkamvar using gmail.com> wrote:
>
>> Mainly, I would like to see the value printed after the print statement
>> like it would appear in a normal R session:
>>
>> print("Hi")
>> #> [1] "Hi"
>> print("Hello")
>> #> [1] "Hello"
>> print("Goodbye")
>> #> [1] "Goodbye"
>>
>>
>> On Fri, Aug 10, 2018 at 11:28 AM Alexandre Courtiol <
>> alexandre.courtiol using gmail.com> wrote:
>>
>>> Hi Zhian,
>>> Could you please explain what behaviour you would like to obtain?
>>> I really don't understand what your problem is from your description...
>>> Alex
>>>
>>> On Fri, 10 Aug 2018 at 12:18, Zhian Kamvar <zkamvar using gmail.com> wrote:
>>>
>>>> Hello,
>>>>
>>>> I know it's good practice to use
>>>>
>>>> if (require("some_package")) {
>>>>   # some code that needs some_package
>>>> }
>>>>
>>>> In R examples that needs a package listed in Suggests.
>>>>
>>>> The problem with this approach is that if there are any print statements
>>>> within this structure, then they only get printed after the braces and
>>>> not
>>>> after the lines like so:
>>>>
>>>> if (TRUE) {
>>>>   print("Hi")
>>>>   print("Hello")
>>>>   print("Goodbye")
>>>> }
>>>> #> [1] "Hi"
>>>> #> [1] "Hello"
>>>> #> [1] "Goodbye"
>>>>
>>>> The only way I can think of circumventing this is by replacing the if
>>>> statement with a stopifnot statement:
>>>>
>>>> stopifnot(require("some_package"))
>>>> # some code that needs some_package
>>>>
>>>> But, I'm not sure if that's okay to do in a function example. Does
>>>> anyone
>>>> have any ideas or suggestions on how to help with this kind of thing?
>>>>
>>>> Cheers,
>>>> Zhian
>>>>
>>>>         [[alternative HTML version deleted]]
>>>>
>>>> ______________________________________________
>>>> R-package-devel using r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-package-devel
>>>>
>>>
>>>
>>> --
>>> Alexandre Courtiol
>>>
>>> http://sites.google.com/site/alexandrecourtiol/home
>>>
>>> *"Science is the belief in the ignorance of experts"*, R. Feynman
>>>
>>
>
> --
> Alexandre Courtiol
>
> http://sites.google.com/site/alexandrecourtiol/home
>
> *"Science is the belief in the ignorance of experts"*, R. Feynman
>

	[[alternative HTML version deleted]]

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