[Rd] In glm explicitly search stats for family functions

[Tim Taylor]

Thank you Duncan

Yes, given Martin's comment it is probably too big a can for the reward.

To other commentators - the example was purely to illustrate what Duncan more clearly articulated (i.e. stats looking for strings on the search path).  In my own code I was evaluating things in an environment whose parent was `basenv()`. I'm now restructuring this as clearly it was a little too restrictive/fragile.

Best

Tim 

On Mon, 9 Mar 2026, at 3:49 PM, Duncan Murdoch wrote:
> On 2026-03-09 7:53 a.m., Tim Taylor wrote:
>> I appreciate there are likely many places where calling a stats function via `::` and without the stats package being loaded could be problematic but would R core have any interest in adapting functions to accommodate this where possible?
>> 
>> The example I ran in to today can be seen below:
>> 
>> ex <- function() {
>>      counts <- c(18,17,15,20,10,20,25,13,12)
>>      outcome <- gl(3,1,9)
>>      treatment <- gl(3,3)
>>      stats::glm(counts ~ outcome + treatment, family = "poisson")
>> }
>> 
>> tools::R(ex)
>> #>
>> #> Call:  stats::glm(formula = counts ~ outcome + treatment, family = "poisson")
>> #>
>> #> Coefficients:
>> #> (Intercept)     outcome2     outcome3   treatment2   treatment3
>> #>   3.045e+00   -4.543e-01   -2.930e-01    6.972e-16    8.237e-16
>> #>
>> #> Degrees of Freedom: 8 Total (i.e. Null);  4 Residual
>> #> Null Deviance:	    10.58
>> #> Residual Deviance: 5.129 	AIC: 56.76
>> 
>> tools::R(ex, env=c("R_DEFAULT_PACKAGES=NULL"))
>> #> Error: error in inferior call:
>> #>   object 'poisson' of mode 'function' was not found
>> 
>> The second call fails due to the following line in glm:
>> 
>> if (is.character(family))
>>          family <- get(family, mode = "function", envir = parent.frame())
>> 
>> A non-breaking patch (AFAICT) could add an additional branch that explicitly searches a lookup of functions in the stats package if the above call to `get` failed.
>> 
>> Again I understand this could very much be a case of, "don't do that", but ...
>
> There are several other cases in stats where functions assume that a 
> function name passed as a string can be found on the search list.  They 
> aren't always consistent about the search order:
>
> C() searches for contr in the stats namespace first, as does 
> make.tables.aovproj().
>
> contrasts() does like glm() for family, it looks in the parent frame.
> ks.test.default() likewise.
>
> make.tables.aovprojlist() looks locally first, but doesn't restrict the 
> search to functions.
>
> I'm not sure I spotted all cases of this, and I didn't look in any other 
> base packages besides stats.
>
> So I think a patch to fix this should determine a consistent approach, 
> and apply it everywhere.  Maybe too big a can of worms?
>
> Duncan Murdoch