the problem is that CINT (i.e. rootcint) can only handle
one level of pre-processor directives (a define in an include
is two levels so that does not work).
I myself never managed to successfully use the -p option because
it tends normally to generate way too much input for rootcint to
handle correctly (maybe Masa can elaborate on this when he is
back from his well deserved holidays). What I would do in your
case is this:
//-------------------------------- v23.h
#include "Rtypes.h"
#include <math.h>
#ifdef __CINT__
# define M_PI 3.14159265358979323846
#endif
double const PI = M_PI;
class V2 {
public:
double X,Y;
V2 ();
V2 (double x0, double y0);
ClassDef(V2,1)
};
//---------------- LinDef.h
#pragma link off all globals;
#pragma link off all classes;
#pragma link off all functions;
#pragma link C++ class V2;
#pragma link C++ global PI;
Now run rootcint and make the so. Starting root and
loading the so one can now type PI and get the
right answer.
Cheers, Fons.
PS: Notice you can also use TMath::Pi() to get Pi.
Pasha Murat wrote:
>
> Hi,
>
> I'm trying to build a shared library to be used by ROOT and I'm having a problem
> with rootcint processing of #define's. After cutting off the source code almost
> everything I ended up with the example enclosed below, showing how I failed to
> make use of
>
> #define M_PI 3.14159265358979323846
>
> directive defined in /usr/include/math.h. I'd appreciate if somebody could
> comment on what's wrong with this example.
>
> Thanks, Pasha.
> --------------------------------------------------------------------------------
>
> There are 3 source files involved:
> ------------------------------------------------------ LinkDef.h
> #ifdef __CINT__
> #pragma link off all globals;
> #pragma link off all classes;
> #pragma link off all functions;
> #endif
> ------------------------------------------------------- v23.hh
> #include "Rtypes.h"
> #include <math.h>
> double const PI = M_PI;
> class V2 {
> public:
> double X,Y;
> V2 ();
> V2 (double x0, double y0);
> ClassDef(V2,1)
> };
> #pragma link C++ class V2;
> -------------------------------------------------------- v23.cc
> #include "v23.hh"
> ClassImp(V2)
>
> V2::V2 () { X = 0.; Y = 0.; }
> V2::V2(double x0, double y0) { X = x0; Y = y0; }
> ---------------------------------------------------------
>
> Now I'm trying to build the library:
>
> ****************************** pass 1.
> /cdf/upgrade/tracking/murat/g3/test/glob>rootcint -f v23_cint.cc -c -I../include LinkDef.h v23.hh
> Error: No symbol M_PI in current scope FILE:v23.hh LINE:5
>
> >>> yes, M_PI is defined in <math.h> via #define, we need to switch
> ON preprocessing.
>
> ***************************** pass 2
> Let's do it. First I'm trying to use '#pragma preprocessor on/off. '
> So v23.hh becomes:
> --------------------------------------------------------- v23.hh
> #include "Rtypes.h"
> #pragma preprocessor on
> #include <math.h>
> double const PI = M_PI;
> #pragma preprocessor off
> class V2 {
> public:
> double X,Y;
> V2 ();
> V2 (double x0, double y0);
> ClassDef(V2,1)
> };
> #pragma link C++ class V2;
> ---------------------------------------------------------
>
> /cdf/upgrade/tracking/murat/g3/test/glob>rootcint -f v23_cint.cc -c -I../include LinkDef.h v23.hh
> Error: No symbol M_PI in current scope FILE:v23.hh LINE:6
>
> >>>>>>>>>> so it looks like '#pragma preprocessor on' by itself changes nothing.
> At ths point I grepp'ed ROOT sourses (development 1.03/01) and it looks like
> this pragma is not used by ROOT.
>
>
> ****************************** pass 3
>
> Then I notice that CINT (rootcint) has a '-p ' directive, which is said to
> turn preprocessing ON.
>
> /cdf/upgrade/tracking/murat/g3/test/glob>rootcint -f v23_cint.cc -c -p -I../include LinkDef.h v23.hh
> gcc: v23.hh: linker input file unused since linking not done
> Note: operator new() masked c
>
> >>>>>>>> OK, it looks better, so let's do the next step:
>
> /cdf/upgrade/tracking/murat/g3/test/glob>gcc -shared -o v23.so -I$ROOTSYS/include -I../include v23.cc v23_cint.cc -lstdc++ -lm
> /cdf/upgrade/tracking/murat/g3/test/glob>root
> No default font loaded
> *******************************************
> * *
> * W E L C O M E to R O O T *
> * *
> * Version 1.02/00 25 July 1997 *
> * *
> * You are welcome to visit our Web site *
> * http://root.cern.ch *
> * *
> *******************************************
>
> CINT/ROOT C/C++ Interpreter version 5.13.17, Jul 5 1997
> Type ? for help. Commands must be C++ statements.
> Enclose multiple statements between { }.
> root [0] gSystem->Load("v23.so")
> Load Error: Dynamic link library /cdf/upgrade/tracking/murat/g3/test/glob/./v23.so can not load
> (int)(-1)
> *** Interpreter error recovered ***
>
> ******************************************* pass 4
>
> It is clear that in this example <math.h> serves only for demonstration.
> Lets comment it out, remove '-p' option and see what happens:
> -------------------------------------------- v23.hh
> #include "Rtypes.h"
> #pragma preprocessor on
> // #include <math.h>
> // double const PI = M_PI;
> #pragma preprocessor off
> class V2 {
> public:
> double X,Y;
> V2 ();
> V2 (double x0, double y0);
> ClassDef(V2,1)
> };
> #pragma link C++ class V2;
> ---------------------------------------------
> /cdf/upgrade/tracking/murat/g3/test/glob>rootcint -f v23_cint.cc -c -I../include LinkDef.h v23.hh
> Note: operator new() masked c
> class V2 in v23.hh line 6 original base of virtual func
> /cdf/upgrade/tracking/murat/g3/test/glob>gcc -shared -o v23.so -I$ROOTSYS/include -I../include v23.cc v23_cint.cc -lstdc++ -lm
> /cdf/upgrade/tracking/murat/g3/test/glob>root
> No default font loaded
> *******************************************
> * *
> * W E L C O M E to R O O T *
> * *
> * Version 1.02/00 25 July 1997 *
> * *
> * You are welcome to visit our Web site *
> * http://root.cern.ch *
> * *
> *******************************************
>
> CINT/ROOT C/C++ Interpreter version 5.13.17, Jul 5 1997
> Type ? for help. Commands must be C++ statements.
> Enclose multiple statements between { }.
> root [0] gSystem->Load("v23.so")
> (int)0
> root [1] V2 a(1.,1.)
> root [2] .p a
> (class V2)272117632
> 0x0 double X=1
> 0x8 double Y=1
> 0x0 private: static class TClass* fgIsA
> 0x0 private: long G__virtualinfo
> --------------------------------------------------------------
>
> now everyting is fine...
-- Org: CERN, European Laboratory for Particle Physics. Mail: 1211 Geneve 23, Switzerland Phone: +41 22 7679248 E-Mail: Fons.Rademakers@cern.ch Fax: +41 22 7677910