Put Python Dispatcher cache in dict, clear it on new registrations. (#88329)
The motivation is that I am going to add the ability to temporarily
install entries to the python dispatcher, and to do that, I need
an easier way to clear the cache. Putting the cache in a dict
centralizes cache clearing in one place. I then add some easy
cache clearing.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88329
Approved by: https://github.com/albanD
