[Python-Dev] PEP 409 update [was: PEP 409 - final?]

[Ethan Furman]

Nick Coghlan wrote:
> FWIW, I expect the implementation will *allow* "raise exc from
> Ellipsis" as an odd synonym for "raise exc". 

Are we sure we want that?  Raising from something not an exception seems 
counter-intuitive (None being the obvious exception).

> I'd want to allow
> "exc.__cause__ = Ellipsis" to reset an exception with a previously set
> __cause__ back to the default state,

Already done.  :)

> at which point the synonym
> follows from the semantics of "raise X from Y" as syntactic sugar for
> "_exc = X; _exc.__cause__ = Y; raise _exc"

I can see where it would make some sense that way, but it still seems odd.

~Ethan~