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[Martin Sandve Alnæs <martinal@xxxxxxxxx>]

Of course if such a class ExpressionWithTimeSupport is generic and useful
enough and/or needed in official dolfin interfaces, the class can be added
to dolfin.

Martin


On 15 February 2013 11:11, Martin Sandve Alnæs <martinal@xxxxxxxxx> wrote:

> A single global time class is _not_ the way to go, that's not composable
> to multiphysics problems with different timescales, etc etc. It's a very
> narrow design for a very particular use case.
>
> However this is designed, it's a necessity that the user creates the "time
> object" (whatever that is) and passes it to whatever parts of the code that
> should share the same view of the time.
>
> The straightforward way to update time across Expression subclasses in C++
> is to make the shared time a member of those classes.
>
> class MyExpr: Expression {
>   MyExpr(shared_ptr<Time> t)> t(t) {}
>   void eval(...) { double now = t->get_time(); ... }
> }
>
> This requires no library support. You can make a base class for
> Expressions with time support in your time solver code.
>
> Martin
>