dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Jun 10, 2008 at 04:41:25PM +0200, Martin Sandve Alnæs wrote:
> Maybe this design works?
> 
> x is coordinates, c is cell info
> 
> class Function
> {
>   virtual void eval(v, x, c) { eval(v, x); }
>   virtual void eval(v, x) { dolfin_error("missing implementation of eval"); }
> };
> 
> class A: Function
> {
>   void eval(v, x) { do_my_thing; }
> };
> 
> class B: Function
> {
>   void eval(v, x, c) { do_my_thing; }
> };
> 
> The assembler always call eval(v,x,c), the user overloads the one
> he wants. There are already lots of redirecting back and forth in
> the Function hierarchy, so the overhead shouldn't become larger.
> If a user-function that depends on cell info is called in a context
> without cell info, i.e. eval(v,x) is called, this triggers an error.
> 
> Inheritance in Python is probably a problem here (SWIG issues).
> Alternatively, name them eval(v,x) and eval_cell(v,x,c) or something
> to solve that problem.

Good, but it becomes a bit messy if we also want to include the other
hidden arguments (see protected section of Function):

  /// Access current facet normal (available during assembly for user-defined function)
  Point normal() const;

  /// Access current facet (available during assembly for user-defined functions)
  int facet() const;

-- 
Anders

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