On 2 June 2011 23:34, Robert Bradshaw <rober...@math.washington.edu> wrote: > On Thu, Jun 2, 2011 at 2:21 PM, mark florisson > <markflorisso...@gmail.com> wrote: >> On 2 June 2011 23:13, Robert Bradshaw <rober...@math.washington.edu> wrote: >>> On Thu, Jun 2, 2011 at 2:03 PM, mark florisson >>> <markflorisso...@gmail.com> wrote: >>> >>>>>>> If anyone is assigning a Cython function to an object and then using >>>>>>> it they're counting on the current non-binding behavior, and it will >>>>>>> break. The speed is probably a lesser issue, which is what benchmarks >>>>>>> are for. >>>>>> >>>>>> If you're binding functions to classes without expecting it to ever >>>>>> bind, you don't really have bitching rights when stuff breaks later >>>>>> on. You should have been using staticmethod() to begin with. And we >>>>>> never said that our functions would never bind :) >>>>> >>>>> No, you're assigning it to an object, counting on being able to call >>>>> it later on. E.g. the following is legal (though contrived in this >>>>> example): >>>>> >>>>> sage: class A: >>>>> ....: pass >>>>> ....: >>>>> sage: a = A() >>>>> sage: a.foo = max >>>>> sage: a.foo([1,2,3]) >>>>> 3 >>>>> >>>>> If instead of len, it was one of our functions, then it would be bad >>>>> to suddenly change the semantics, because it could still run but >>>>> produce bad answers (e.g. if we had implemented max, suddenly a would >>>>> be included in the comparison). This is why I proposed raising an >>>>> explicit error as an intermediate step. >>>>> >>>>> If we don't promise anything, the contract is whatever the code does. >>>>> That's the problem with not having a specification (which would be >>>>> really nice, but is a lot of work). >>>> >>>> Functions on objects never get bound, they only get bound if they are >>>> on the class. So your code would still work with binding functions. >>> >>> True. It would still break "A.foo = max" though. I'm not saying we >>> should support or encourage this, but lets break it hard before we >>> break it subtly. >> >> Again, such code is highly fragile and frankly incorrect to begin >> with, as it's based on the assumption that "Cython functions" never >> get bound. > > I agree, but I bet there's code out there depending on it, in > particular workarounds for our current broken semantics will > themselves break.
Workarounds wouldn't break, as they would wrap the non-binding function in another object, and implement __get__ to return a new object that, when called, would call the original function with 'self' as the first argument. >> Getting functions (defined outside of class bodies) to bind >> in classes is a feature, I sometimes found myself to want it. So >> basically an error would be fine, but it would prevent normal usage as >> we have it in Python. > > The error would just be for a transition period. The transition period would be for an entire release? > - Robert > _______________________________________________ > cython-devel mailing list > cython-devel@python.org > http://mail.python.org/mailman/listinfo/cython-devel > _______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
