[Rd] Improving user-friendliness of S4 dispatch failure when mis-naming arguments?

[Michael Chirico]

I forwarded that along to the original reporter with positive feedback
-- including the argument names is definitely a big help for cuing
what exactly is missing.

Would a patch to do something similar for S4 be useful?

On Thu, Aug 10, 2023 at 6:46 AM Hadley Wickham <h.wickham using gmail.com> wrote:
>
> Hi Michael,
>
> I can't help with S4, but I can help to make sure this isn't a problem
> with S7. What do you think of the current error message? Do you see
> anything obvious we could do to improve?
>
> library(S7)
>
> dbGetQuery <- new_generic("dbGetQuery", c("conn", "statement"))
> dbGetQuery(connection = NULL, query = NULL)
> #> Error: Can't find method for generic `dbGetQuery(conn, statement)`:
> #> - conn     : MISSING
> #> - statement: MISSING
>
> Hadley
>
> On Wed, Aug 9, 2023 at 10:02 PM Michael Chirico via R-devel
> <r-devel using r-project.org> wrote:
> >
> > I fielded a debugging request from a non-expert user today. At root
> > was running the following:
> >
> > dbGetQuery(connection = conn, query = query)
> >
> > The problem is that they've named the arguments incorrectly -- it
> > should have been [1]:
> >
> > dbGetQuery(conn = conn, statement = query)
> >
> > The problem is that the error message "looks" highly confusing to the
> > untrained eye:
> >
> > Error in (function (classes, fdef, mtable)  :   unable to find an
> > inherited method for function ‘dbGetQuery’ for signature ‘"missing",
> > "missing"’
> >
> > In retrospect, of course, this makes sense -- the mis-named arguments
> > are getting picked up by '...', leaving the required arguments
> > missing.
> >
> > But I was left wondering how we could help users right their own ship here.
> >
> > Would it help to mention the argument names? To include some code
> > checking for weird combinations of missing arguments? Any other
> > suggestions?
> >
> > Mike C
> >
> > [1] https://github.com/r-dbi/DBI/blob/97934c885749dd87a6beb10e8ccb6a5ebea3675e/R/dbGetQuery.R#L62-L64
> >
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>
>
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