[Python-Dev] Pathlib enhancements - acceptable inputs and outputs for __fspath__ and os.fspath()

[Stephen J. Turnbull]

Random832 writes:
 > On Thu, Apr 14, 2016, at 03:02, Stephen J. Turnbull wrote:

 > > I have a strong preference for str only, because I still don't see a
 > > use case for polymorphic __fspath__.
 > 
 > Ultimately we're talking about redundancy and performance here.

Ultimately, yes.  Right now I have some epithets for you:  Premature!
Optimization!!  Get thee behind me, Satan!

More seriously, concrete use cases where this overhead matters?

Church-of-Don-Knuth-member-ly y'rs,