dolfin team mailing list archive

[Dag Lindbo <dag@xxxxxxxxxx>]

Dag Lindbo wrote:
> Ola Skavhaug wrote:
> > Dag Lindbo skrev den 09/04-2008 følgende:
> > > Hello again!
> > >
> > > Why is it not possible any longer to get the Vector associated with a 
> > > Function? E.g:
> > >
> > > #include <dolfin.h>
> > > using namespace dolfin;
> > >
> > > int main()
> > > {
> > >    Function u;
> > >    Vector& v = u.vector();
> > > }
> >
> > int main()
> > {
> >      Function u;
> >      Vector v;
> >      v = u.vector();
> >      return 0;
> > }
> >
> > Should work. A Function returns a GenericVector reference, and the Vector
> > reference needs to be a Vector. Then the operator= in Vector is 
> > applied in the
> > assignment.
> >
> > Ola
>
> Ola,
>
> Sorry if I'm this is a stupid/incorrect observation. What you propose is 
> a a deep copy of the vector. So something like
>
> uBlasVector& vv = *(v.instance());
> vv[0] = 1000.32;
>
> has no impact on the data owned by u. uBlas only has deep copy 
> semantics, which are invoked in dolfin::Vector::operator= (i.e. *vector 
> = *x; )
>
> Is this really what we want?
>
> /Dag

Seems I'm also sloppy with grammar today. My previous post may sound 
offensive towards Ola, but I only meant to pre-excuse _myself_ in case 
my understanding of C++ has deserted me this evening. /Dag

> >  
> > > error: invalid initialization of reference of type ‘dolfin::Vector&’ 
> > > from expression of type ‘dolfin::GenericVector’
> > >
> > > na55:cpp > scons
> > > c++ -o test.o -c -Wall -pipe -ansi -g -Werror -O2 -pthread -DDEBUG 
> > > -DNDEBUG -DPACKAGE_VERSION="0.7.2" -DHAS_UMFPACK=1 -DHAS_GTS=1 
> > > -I/usr/local/include 
> > > -I/usr/lib/python2.5/site-packages/numpy/core/include 
> > > -I/usr/include/suitesparse -I/usr/include/python2.5 
> > > -I/usr/include/libxml2 -I/usr/include/glib-2.0 
> > > -I/usr/lib/glib-2.0/include test.cpp
> > > test.cpp: In function ‘int main()’:
> > > test.cpp:8: error: invalid initialization of reference of type 
> > > ‘dolfin::Vector&’ from expression of type ‘dolfin::GenericVector’
> > > cc1plus: warnings being treated as errors
> > > test.cpp:8: warning: unused variable ‘v’
> > > scons: *** [test.o] Error 1
> > >
> > > I hope this functionality hasn't been removed.
> > >
> > > /Dag
> > > _______________________________________________
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