On Sun, 02 May 2010 17:09:36 +1000, Lie Ryan wrote: > On 05/02/10 10:58, Steven D'Aprano wrote: >> On Sun, 02 May 2010 05:08:53 +1000, Lie Ryan wrote: >> >>> > On 05/01/10 11:16, Steven D'Aprano wrote: >>>> >> On Fri, 30 Apr 2010 12:34:34 -0400, D'Arcy J.M. Cain wrote: >>>> >> >>>> >> In practice though, I think that's a difference that makes no >>>> >> difference. It walks like an operator, it swims like an operator, >>>> >> and it quacks like an operator. >>>> >> >>>> >> >>> > Nope it's not. A full-time operator in python have a reflected >>> > version (e.g. __radd__), which dot does not have. >> What are the reflected versions of __eq__ and __ne__ (binary == and != >> operators)? > > Python do not have them now, but it does make sense if python have > them[1]. OTOH, given current python's language semantic, __rgetattr__ > doesn't make any sense; adding __rgetattr__ would require a quite > fundamental change to the language's semantic, primarily how attribute > resolution works. > > [1] though they'd probably be dismissed as bad idea since equality and > inequality are supposed to be a symmetric relation; reflected > (in)equality makes it way too easy to break that premise > >> And __neg__, __pos__ and __inv__ (for the unary - + and ~ operators)? >> >> And the three-argument form of __pow__ for power(1, 2, x)? > > I know you're a famed nitpicker, but don't be silly, reflected operator, > by definition, only makes sense for binary operator.
Binary operators aren't the only kind of operator, and you claimed that: "A full-time operator in python have a reflected version". But there are full-time operators that don't have reflected versions, so your claim is just *wrong*. It would still be wrong even if you had limited yourself to binary operators. I have agreed with you that there are useful things people might want to do (e.g. function composition) that you can't do because the "dot operator" isn't a *real* operator with exactly the same semantics as "plus operator", "multiply operator" and friends. I think we're in violent agreement, and merely disagreeing over semantics. There's no need to continue arguing against a position I haven't actually taken :) -- Steven -- http://mail.python.org/mailman/listinfo/python-list
