On Tuesday, May 27th, 2025 at 9:13 AM, Kurt Hornik <kurt.hor...@wu.ac.at> wrote:
> > > > > > Trevor Davis writes:
>
>
> Thanks.
>
> This is really about what
>
> library("foo", include.only = "fun2")
>
> should do if package 'foo' was already attached and the include.only
> contradicts a previous specification.
>
> In principle, one could look into allowing the underlying
> attachNamespace() to add more exports into the package environment (the
> 'only' in 'include.only' might suggest differently, but we would have to
> live with that). However, using detach/attach is not the right way of
> doing this, as it possibly modifies the search path and may trigger
> hooks that should not be triggered. Doing it right would probably need
> an .Internal and hence be a lot of work ...
>
> What definitely needs attention is the fact that currently the above is
> silently ignored. So at least for now we should teach attachNamespace()
> to throw a suitably classed error if called with include.only that
> contradicts a previous specification.
>
> Contributions welcome :-)
Some work has been done on that front during last week's r-dev-day
with Ella Kaye and Philippe Grosjean [1]. After some more thinking, I
think we haven't been stringent enough, and would suggest that the
user should be alerted as soon as what they want to attach doesn't
match exactly what is already on the search path. Something along the
lines of (the warning/message can of course be amended).
These two situations are OK, given that exactly the same set is asked
for repeated, either with a limited set of functions:
> library("Matrix", include.only = "isDiagonal")
> library("Matrix", include.only = "isDiagonal") ## ok
or, in a new session, with the whole package:
> library("Matrix", include.only = "isDiagonal")
> library("Matrix", include.only = "isDiagonal") ## ok
Below, (again, in a new session) the user could be mislead that either
only qr would be attached (and isDiagonal not anymore), or all
Matrix's exported symbols:
> library("Matrix", include.only = "isDiagonal")
> library("Matrix", include.only = "qr") ## warn
Warning message:
In library("Matrix", include.only = "qr") :
The package 'Matrix' is already loaded with a different set of functions.
Please detach() it first.
> library("Matrix") ## warn
Warning message:
In library("Matrix") :
The package 'Matrix' is already loaded with a different set of functions.
Please detach() it first.
In the following cases, a subset is asked after all symbols are
attached, which also triggers a warning/message:
> library("Matrix")
> library("Matrix", exclude = "isDiagonal") ## warn
Warning message:
In library("Matrix", exclude = "isDiagonal") :
The package 'Matrix' is already loaded with a different set of functions.
Please detach() it first.
> library("Matrix", include.only = "isDiagonal") ## warn
Warning message:
In library("Matrix", include.only = "isDiagonal") :
The package 'Matrix' is already loaded with a different set of functions.
Please detach() it first.
If this is a good way forward, I would be happy to carry on that work.
Laurent
[1] https://github.com/r-devel/r-dev-day/issues/48
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