On Saturday 28 November 2009 00:53:51 Anders Logg wrote: > On Fri, Nov 27, 2009 at 11:59:52PM -0800, Johan Hake wrote: > > Hello! > > > > I have not pushed anything, but Expressions should be up to shape now, > > and I am working on simplifying the logic in other places of > > expression.py > > > > I do not like the implementation of the dim method. It is used to read a > > user defined value dimension and then discarded. I suggest that we add a > > value_shape attribute to the dolfin.Expression class. If not set by the > > user it is by default (), i.e., a scalar Expression. > > > > class MyExpression(Expression): > > value_shape = (2,) > > def eval(self, values, x): > > values[0] = 1 > > values[1] = 1 > > > > The dim name is also only making sense for Vector Expressions, where I > > think a value_shape attribute makes sense for all occasions. A > > value_shape for scalar Expression will still be the default. > > I think a dim method makes more sense than adding a variable since it > is consistent with eval: Then all data a subclassed Expression needs > to give is defined by a member function.
Ok, but then I think we should keep it and not just pop it from the dictionary, so a user can use it after the class is created. Is it very intuitive that dim stands for value dimension? Should we call it value_dim or value_dimension? > If we need value_shape and value_dimension (which is good to have), > can't we just store those values as _value_shape, _value_dimension > after we have figured out the shape and provide member functions that > return those values? We already have value_rank and value_dimension in the cpp interface. So it might be overkill to have these for no other sake. > Also note the clever/simplified interface for dim() allowing (1) not > to overload it for scalars and (2) to return the just the vector > dimension for vectors: n instead of (n,)). Yes, I notices. Johan > -- > Anders > > > After creation and instantiation we then have an object that have both a > > shape method (from ufl.Function) and a value_shape attribute from the > > subclassing definition. > > > > What you think. > > > > Johan > > > > _______________________________________________ > > Mailing list: https://launchpad.net/~dolfin > > Post to : [email protected] > > Unsubscribe : https://launchpad.net/~dolfin > > More help : https://help.launchpad.net/ListHelp > _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
