R help - Oct 2018 - Should package be reinstalled when exterbal library is changed

Dear R-experts,

Some packages need external libraries to be installed. For example ncdf4 
needs netcdf library or flextable need pandoc.

When there is new version of external library, should the R package be 
installed again to use the new external version, or do the package finds 
itself the new version? Perhaps the answer is "It depends on the 
package", and so how to know if it requires new compilation or not ?

Thanks

Marc

Hi Marc,
Normally updating external libraries would not require re-installing an R
package that uses it.
The R package will be able to "find" the new one, because the updated
library would be in the same place (sort of) as the previous library.
On a linux system this is handled by system soft links such as foo.so -->
foo.so.1 changes to foo.so --> foo.so.2
when a version '2' of the foo shared object (the .so.2) is now available
to
replace version 1.
On Windows systems a .DLL corresponds to the linux .so.

While you won't need to re-install an R package you will need to start a
new R session.

At a more advanced level you actually can explicitly tell R which .so (or
.dll) files to pull in via the function dyn.load()
See ?dyn.load for details.

HTH,
Eric





On Tue, Oct 30, 2018 at 5:06 PM Marc Girondot via R-help <
r-help at r-project.org> wrote:
> Dear R-experts,
>
> Some packages need external libraries to be installed. For example ncdf4
> needs netcdf library or flextable need pandoc.
>
> When there is new version of external library, should the R package be
> installed again to use the new external version, or do the package finds
> itself the new version? Perhaps the answer is "It depends on the
> package", and so how to know if it requires new compilation or not ?
>
> Thanks
>
> Marc
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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