Just about every implementation of every D-Bus interface in every CM uses this idiom:

#define IMPLEMENT(x) tp_svc_channel_implement_##x (\
    klass, gabble_im_channel_##x)
  IMPLEMENT(close);
  IMPLEMENT(get_channel_type);
  IMPLEMENT(get_handle);
  IMPLEMENT(get_interfaces);
#undef IMPLEMENT

I always end up cargo-culting this, and it's easy to get wrong, particularly if I accidentally copy from somewhere that reimplements most but not all of the methods.

It'd be nice to have this boilerplate in the documentation of the interface type, as a canonical source.