Setting compilation options specified by external scripts

[rayohauno]

Hi,

I'm compiling a project that uses some precompiled library (I'm trying to integrate
R C++ code (see http://www.r-project.org/) in a common C++ project). In order to
compile that library it is required to pass to the g++ linker some options (flags?).
The options (flags) may vary from system to system, so one must call a script (or program)
that replies with the right/specific flags for each system.

I do that writing in (right click on the project name) -> Settings -> Linker -> Options the
following:

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`usr/lib64/R/bin/Rscript -e "Rcpp:::LdFlags()"`

and it works. In fact if in a terminal I write:

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$ /usr/lib64/R/bin/Rscript -e "Rcpp:::LdFlags()"

its replies:

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-L/usr/local/lib/R/site-library/Rcpp/lib -lRcpp -Wl,-rpath,/usr/local/lib/R/site-library/Rcpp/lib

and that is ok. Now, the path to the script may also vary from system to system. In my
case the path is:

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/usr/lib64/R/bin/

from it, the "first part":

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/usr/lib64/R/

is the system specific. This first part of the path can be obtained calling an executable named R that
is exported to the system PATH (when R is installed) trough the following command:

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$ R RHOME

which returns:

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/usr/lib64/R

So I want to use that in order to make non system specific the "options" line
that I pass to the compiler. I have tried two things. One is to change:

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`usr/lib64/R/bin/Rscript -e "Rcpp:::LdFlags()"`

by:

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`$(R RHOME)/bin/Rscript -e "Rcpp:::LdFlags()"`

but it doesn't work (I'm not a linux expert). Then I have tried
by means of exporting what R RHOME returns. That is, in:
(right click on project name) -> Settings -> PreBuild
I add the follwong command line to run in the pre-build event:

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export R_HOME=$(R RHOME)

and then change:

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`usr/lib64/R/bin/Rscript -e "Rcpp:::LdFlags()"`

by:

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`$(R_HOME)/bin/Rscript -e "Rcpp:::LdFlags()"`

but it also doesn't work.

Which is the right way of do that?

Best Regards

[eranif]

In the linker options, add this:

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$(shell $(shell R RHOME)/bin/Rscript -e "Rcpp:::LdFlags()")

It will do what you want.
Eran

[rayohauno]

Thanks Eran,

Now, I'm figuring out that this is "Make coding" (I do not know how to name this, I'm not a programmer). Also, after post I have tried
something similar, I've tried this (between several other intents):

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$(shell $(R RHOME)/bin/Rscript -e "Rcpp:::LdFlags()")

but it does not work. I was close.

Best Regards