I'm tired of having to cook up hard-coded fptr and gptr arguments to pass to methods like System::project_vector() and ExactSolution::attach_exact_value(); I'd prefer to be able to pass in function objects instead.
But I also want to avoid breaking backwards compatibility, so we need some species of function object, a WrapperFunction, to be the argument to these methods, so that function pointers passed in can be implicitly converted to WrapperFunction temporaries. But I don't want to force everyone to subclass WrapperFunction, so it needs to also be constructable from any FunctionBase-derived object. Now here's the dilemma: Strategy A: If we have WrapperFunction store a copy of the FunctionBase-derived object, then for that copy to be useful we need a FunctionBase::clone() method to avoid slicing. Strategy B: If we have WrapperFunction instead store a FunctionBase*, then it can't be constructed from a temporary. I.e. users won't be able to do: // case 1 ExactSolution::attach_exact_value (ZeroFunction()); // grossly contrived example They'll have to do: // case 2 ZeroFunction z; ExactSolution::attach_exact_value (z); Fortunately we'll be taking a non-const FunctionBase& argument, so case 1 will give us a compile-time error rather than a dangling pointer, but it's still a tradeoff. I'm leaning towards Strategy B: slightly more annoying syntax for new functor users, but no chance of breaking existing code from users who have their own classes derived from FunctionBase. Before I finish implementing it: anyone else have ideas or preferences? --- Roy ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Libmesh-devel mailing list Libmesh-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-devel
