[Rd] In glm explicitly search stats for family functions

[Serguei Sokol]

Le 09/03/2026 à 12:53, Tim Taylor a écrit :
> 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.
You can do it on your own side by modifying the function 'ex' like:

ex <- function() {
     counts <- c(18,17,15,20,10,20,25,13,12)
     outcome <- gl(3,1,9)
     treatment <- gl(3,3)
     require(stats)
     stats::glm(counts ~ outcome + treatment, family = "poisson")
}

Note "require(stats)" before glm() call. In a classical R env, this is almost a no-cost operation because stats is already attached and in R_DEFAULT_PACKAGES=NULL
  case, it does what you need.

Best,
Serguei.

>
> Again I understand this could very much be a case of, "don't do that", but ...
>
> Regards
>
> Tim
>
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