[R-pkg-devel] "Undefined global functions or variables" locally but NOT on GitHub

[Duncan Murdoch]

Yes, the rules for visibility of objects in the `data` directory are 
somewhat strange, but they are documented in "Writing R Extensions", 
section 1.1.6.  They're also summarized here: 
https://stackoverflow.com/a/79122709 .

In defence of the strange rules:  you don't have to use them unless you 
choose to do so. If you want "normal" visibility rules for data, just 
create it using code in the R directory.  Then your data will always be 
visible to functions in your package, and if you export it in the 
NAMESPACE file, always visible to users of your package using the same 
rules as for exported functions.

Duncan Murdoch

On 2025-10-15 12:08 p.m., Spencer Graves wrote:
> Thanks, Duncan.
> 
> 
> This is the first package I've created trying to follow Wickham and
> Bryan, R Packages, including using roxygen2. That DESCRIPTION file
> includes "LazyData: true". I don't remember if I used
> "usethis::use_data()", but I probably did.
> 
> 
> I was surprised that I had to use "::" inside "tests/testthat/test-*.R"
> to access a dataset defined in that package! And I seemed to get the
> problem only on my local computer while all 5 standard GitHub Actions
> seemed not to need that.
> 
> 
> That's what led me to impose upon the time of the experts who contribute
> to this email list.
> 
> 
> Thanks again, Spencer Graves
> 
> 
> On 10/15/25 09:52, Duncan Murdoch wrote:
>> On 2025-10-14 5:16 a.m., Chris Black wrote:
>>>
>>>
>>>> On Oct 14, 2025, at 1:38 AM, Georgi Boshnakov
>>>> <georgi.boshnakov using manchester.ac.uk> wrote:
>>>>
>>>> So, you can't access them with the '::' operator, you need to use
>>>> data().
>>>
>>> You can, though!
>>>
>>> ```
>>> % R --vanilla -q -e 'datasets::AirPassengers'
>>>> datasets::AirPassengers
>>>        Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
>>> 1949 112 118 132 129 121 135 148 148 136 119 104 118
>>> 1950 115 126 141 135 125 149 170 170 158 133 114 140
>>> 1951 145 150 178 163 172 178 199 199 184 162 146 166
>>> 1952 171 180 193 181 183 218 230 242 209 191 172 194
>>> 1953 196 196 236 235 229 243 264 272 237 211 180 201
>>> 1954 204 188 235 227 234 264 302 293 259 229 203 229
>>> 1955 242 233 267 269 270 315 364 347 312 274 237 278
>>> 1956 284 277 317 313 318 374 413 405 355 306 271 306
>>> 1957 315 301 356 348 355 422 465 467 404 347 305 336
>>> 1958 340 318 362 348 363 435 491 505 404 359 310 337
>>> 1959 360 342 406 396 420 472 548 559 463 407 362 405
>>> 1960 417 391 419 461 472 535 622 606 508 461 390 432
>>> ```
>>>
>>> This is also explicit in R Internals 1.17 ([1], emphasis added):
>>> "Lazy-load databases are loaded into the exports for a package, but
>>> not into the namespace environment itself. Thus they are visible when
>>> the package is attached, ***and also via the :: operator.***”
>>>
>>> [1] https://cran.r-project.org/doc/manuals/r-release/R-ints.html#Lazy-
>>> loading
>>
>> That's true provided the data is lazy-loaded.  The default is "LazyData:
>> false", but "LazyData: true" is a pretty common choice because
>> usethis::use_data() puts that in DESCRIPTION.
>>
>> Duncan Murdoch
>>
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>