Re: How to detect classes with a count_elements handler in userland?

On 16.11.2016 at 22:02, Nikita Popov wrote: > On Mon, Nov 14, 2016 at 2:22 PM, Christoph M. Becker <cmbecker69@gmx.de> > wrote: > >> On 13.11.2016 at 22:10, Craig Duncan wrote: >> >>>> How about just making those classes implement the interface instead? >>> >>> Christoph pointed out that there may be classes in extensions that use >>> count_elements. >> >> Furthermore, letting those classes implement Countable could break BC. > > How would this break BC? > > SXE even already has a count() method, and count_elements respects > overrides of that method. Clearly SXE is supposed to implement Countable, > it was simply forgotten. Thinking about it, we most likely don't have to be concerned with some *theoretic* BC break (such as !(instance of Countable)). Thanks! -- Christoph M. Becker