Hi Davide, On 2009-11-12 10:22, Davide Cesari wrote: > Hi Arjen, > > Arjen Markus ha scritto: >> Hi Davide, Hazen, >> >> yes, g77 is complaining because of the "implicit none" statements. >> I have now added "external floor" and "real*8 floor", so the error >> messages are gone. >> >> The second (warning) message is about calling plslabelfunc with a >> literal 0, rather than a procedure name. gfortran ignores this, >> but g77 gives a warning. I am not sure how to proceed here - I >> will look into it later on. > > Apart from being a warning, this will probably not work because a > literal 0 means passing a pointer to a zero value, not a NULL pointer, > so the C will see it as a valid pointer and try to call it with > unpredictable results. I think there is no clean, portable way to pass a > null pointer in f77; the only solution in my view here -ugly, I agree- > if f77 support has to be maintained, is to change the API for fortran > and do some kind of plslabeldisablefunc() or something like that. > In f90 it can be done cleanly by defining an interface to 2 subroutines, > one receiving a procedure and one receiving an integer, the second can > then call a C wrapper passing the null pointer, something similar is > done in f90gl for glutNullFunc (see: http://math.nist.gov/f90gl/ ) > Hope this helps, Davide >
Actually, that is a very good point! The current Fortran 95 bindings do not take care of this properly either. I will implement your suggestion. For the F77 bindings we can not do anything like that, except to check whether the _literal_ value at the address is zero (though it may not be legal to take the _value_ of an address that is actually a function pointer ...) Regards, Arjen ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
