Resource index

Simulation Modeling Toolkit (SMTK) Design
1

@tj.corona
It looks like resource classes only provide a virtual method to obtain a Resource::Index. What would you think about adding

class Foo : public smtk::resource::Resource
{
  static constexpr Index TypeIndex =
    std::type_index(typeid(Foo)).hash_code());
};

to resources so that we can do things like ask a resource manager for resources of a compile-time-known type?

smtk::resource::Manager::Ptr mgr;
auto rsrcs = mgr->resources().get<IndexTag>().equal_range(Foo::TypeIndex);
for (rsrc : rsrcs)  { ... }
2

Makes sense to me. Better still would be to put it in DerivedFrom.h, so it doesn’t have to be placed in every resource (hooray for CRTP!).

3

Sadly, classes cannot provide constexpr to their own index (since typeid is ill-formed before the class is fully defined and thus no class member can hold its own Index). However, it is possible to provide a static method to compute it.

4

To close this out, here is the merge request that implemented this feature.