dolfin team mailing list archive

[Johan Hake <hake@xxxxxxxxx>]

On Saturday 18 October 2008 23:23:24 Anders Logg wrote:
> On Sat, Oct 18, 2008 at 10:16:32PM +0200, Johan Hake wrote:
> > On Saturday 18 October 2008 21:24:53 Anders Logg wrote:
> > > On Thu, Oct 16, 2008 at 03:38:01PM +0200, Martin Sandve Alnæs wrote:
> > > > "in" is a reserved keyword in python. Suggestions: "f.in_space(V)" or
> > > > "f.in_function_space(V)" or "f.member(V)"
> > >
> > > How about keeping u.in(V) in C++ and then map it to something suitable
> > > in Python so that one may write
> > >
> > >   if u in V:
> > >       ...
> > >
> > > in Python. Does anyone know how to do that?
> >
> > There is a problem in the logic here. In c++ you ask the function if it
> > is in a certain FunctionSpace, but the python code "u in V" would check
> > if u is in V by calling V.__contains__(u). To make it more consistent we
> > could implement the 'in' function in FunctionSpace, and then just rename
> > 'in' to __contains__.
> >
> > You could also keep it the way it is and then rename Function.in to let
> > say Function._in and then extend FunctionSpace with
> >
> >   def __contains__(self,u).
> >       assert(u,Function)
> >       return u._in(self)
> >
> > But then we would have different logics in c++ and python.
> >
> > Johan
>
> I think that would be ok, considering it is Python that maps "in" to
> "contains". The logic and notation from a user perspective would be
> the same in C++ and Python:
>
>   if (u.in(V))
>   {
>
>   }
>
>   if u in V:

I see your point and I agree. 

My logical error was attached to who implemented what. But to get the nice and 
from a user perspective logical syntax you present above, we need to 
implement it differently in c++ and python.

Good night! ;)

Johan