[R] Repeated use of dyn.load().

[Eric Berger]

Good question Rolf.
Rui, thanks for pointing out dyn.unload.
When I started using Rcpp a couple of years ago I got burned by stale .so
enough times that I adopted a policy of recompile-then-start new R session.
My workflow does not include Rolf's "brazillion" repeats, so the overhead
of this approach has not been too painful.
The documentation for dyn.unload (via ?dyn.unload) includes the following
statement:

"The function dyn.unload unlinks the DLL. Note that unloading a DLL and
then re-loading a DLL of the same name may or may not work: on Solaris it
uses the first version loaded."

Eric



On Thu, Mar 1, 2018 at 2:21 PM, Rui Barradas <ruipbarradas at sapo.pt> wrote:

> Hello,
>
> In such cases, with C code, I call dyn.unload before loading the modified
> shared lib again.
> I don't know if this changed recently, but it used to be needed or else R
> wouldn't load the new lib. When I call dyn.unload followed by dyn.load I
> never had problems.
> (Or the other way around, call dyn.unload before modifying the C code.)
>
> Hope this helps,
>
> Rui Barradas
>
> On 3/1/2018 8:52 AM, Rolf Turner wrote:
>
>>
>> I am working with a function "foo" that explicitly dynamically loads a
>> shared object library or "DLL", doing something like dyn.load("bar.so").
>>  This is a debugging exercise so I make changes to the underlying Fortran
>> code (yes, I acknowledge that I am a dinosaur) remake the DLL "bar.so" and
>> then run foo again.  This is all *without* quitting and restarting R.  (I'm
>> going to have to do this a few brazillion times, and
>> I want the iterations to be as quick as possible.)
>>
>> This seems to work --- i.e. foo seems to obtain the latest version of
>> bar.so.  But have I just been lucky so far?  (I have not experimented
>> heavily).
>>
>> Am I running risks of leading myself down the garden path?  Are there
>> Traps for Young (or even Old) Players lurking about?
>>
>> I would appreciate Wise Counsel.
>>
>> cheers,
>>
>> Rolf Turner
>>
>>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posti
> ng-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

	[[alternative HTML version deleted]]