R help - Jul 2006 - Assistance with dll's to use with dyn.load

After having browsed the documentation for a while without discovering what I am
looking for, maybe one of you would know ...

What I want to do:
I have two fortran files MC.f and ESCA.f. In MC.f there is a call to a routine
called lpost. This routine (lpost) is defined (among other things) in ESCA.f.
Under linux, I can do the following:
	R CMD SHLIB MC.f
and
	R CMD SHLIB ESCA.f
followed by
	dyn.load("ESCA.so",local=FALSE)
	dyn.load("MC.so")
(see point LINUX for some more)



Under windows, trying to Rcmd SHLIB MC.f will either:
	also compile ESCA.f and then run dlltools with ESCA.o yielding one MC.dll (if
ESCA.f is in the same directory as MC.f)
	or fail since the symbol lpost is missing.
In the first case, dyn.load("MC.dll") will then work.



What I would like to have under linux:
	MC and ESCA turned into separate shared libraries (.so or .dll) 
	be able to 
	dyn.load("ESCA.so", local=FALSE); dyn.load("MC.so")
	... work work work ...
	and then
	dyn.unload("ESCA.so"); dyn.load("SomethingElse.so") which
also contains the symbol lpost
	(so, I would like to unload the symbol lpost and replace it by something else)
	in the (good?) old times using S on unix running on a DECstation stuff like
this was possible, but I never could get it working with R and linux.


In windows, I would like the same operation:
	dyn.load("ESCA.dll"); dyn.load("MC.dll")
	work work work
	and then 
	dyn.unload("ESCA.dll"); dyn.load("SomethingElse.dll") which
also contains the symbol lpost
is this possible? I see that the parameters local and now are ignored in
dyn.load for windows but I don't grasp the full meaning.


Summary questions:
1. what are the proper parameters for (Windows) Rcmd.exe SHLIB MC.f such that it
does not complain about a non existing name "lpost"?
2. how can I unload the container of "lpost" such that I can replace
it while R continues running (under Windows and Linux)?

Sorry for lengthy explanation.



Christian Ritter
Senior Statistical Consultant
Analytical and Statistical Services
Shell Coordination Centre S.A.
Monnet Centre International Laboratory, Avenue Jean Monnet 1, B-1348
Louvain-La-Neuve, Belgium

Tel: +32 10 477  349 Fax: +32 10 477 219
Email: christian.ritter@shell.com
Internet: http://www.analyticalsolutions4u.eu


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