dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, Apr 03, 2008 at 10:31:29PM +0200, Martin Sandve Alnæs wrote:
> 2008/4/3, Anders Logg <logg@xxxxxxxxx>:
> > On Thu, Apr 03, 2008 at 10:21:04PM +0200, kent-and@xxxxxxxxx wrote:
> >  > > 2008/4/3, kent-and@xxxxxxxxx <kent-and@xxxxxxxxx>:
> >  > >> > 2008/4/3, Anders Logg <logg@xxxxxxxxx>:
> >  > >>  >> On Thu, Apr 03, 2008 at 07:47:13PM +0200, Martin Sandve Alnæs wrote:
> >  > >>  >>  > We only talked about create() the other day, copy() can still be
> >  > >>  >>  > useful! Or does the factory duplicate this functionality?
> >  > >>  >>
> >  > >>  >>
> >  > >>  >> No, but Kent has added an assignment operator:
> >  > >>  >>
> >  > >>  >>   GenericVector* y = x.factory().createVector();
> >  > >>  >>   *y = x;
> >  > >>  >
> >  > >>  > Ok, but the assignment operator doesn't exist in Python, so some
> >  > >>  > variant of the copy function may still be needed. Could be just a
> >  > >>  > wrapper for the two lines above.
> >  > >>
> >  > >>
> >  > >>
> >  > >> PyDolfin has assign:
> >  > >>  dolfin_function_pre.i:%rename(assign) dolfin::Function::operator=;
> >  > >>
> >  > >>
> >  > >>
> >  > >>
> >  > >>  >
> >  > >>  > But the current default implementation of operator= (just return
> >  > >>  > *this;) isn't good, it should be abstract or at least raise an error
> >  > >>  > somehow.
> >  > >>  >
> >  > >>
> >  > >>
> >  > >> It did not compile when it was defined as an abstract function. But I
> >  > >>  agree completely. You probably have a fix, I didn't manage.
> >  > >
> >  > > I didn't know virtual operators were allowed at all in C++, but simply
> >  > > calling dolfin_error in there is one solution (I do this in Python
> >  > > some times to "simulate" pure virtual functions).
> >  > >
> >  >
> >  > Then I get a warning:
> >  >
> >  > cc1plus: warnings being treated as errors
> >  > ./dolfin/la/GenericVector.h: In member function 'virtual const
> >  > dolfin::GenericVector& dolfin::GenericVector::operator=(const
> >  > dolfin::GenericVector&)':
> >  > ./dolfin/la/GenericVector.h:111: warning: no return statement in function
> >  > returning non-void
> >  > scons: *** [dolfin/elements/ProjectionLibrary.os] Error 1
> >  > scons: building terminated because of errors.
> >
> >
> > Normally, one can trick the compiler by doing something like
> >
> >   return *(new GenericVector()); // code will never be reached
> >
> >  but this won't work here since GenericVector is not a concrete type so
> >  it's not possible to instantiate it. And there are no other subclasses
> >  to use since they should not be known to GenericVector...
> 
> Nothing wrong with the "return *this;" that was there.

Yes, of course... I'm getting tired. :-)

-- 
Anders