mark florisson, 07.05.2012 18:18: > On 7 May 2012 17:16, mark florisson wrote: >> On 7 May 2012 17:12, Stefan Behnel wrote: >>> Dag Sverre Seljebotn, 07.05.2012 18:07: >>>> On 05/07/2012 06:04 PM, mark florisson wrote: >>>>> On 7 May 2012 12:10, Stefan Behnel wrote: >>>>>> BTW, is there a reason why we shouldn't allow a "not None" declaration >>>>>> for >>>>>> cdef functions? Obviously, the caller would have to do the check in that >>>>>> case. >>>>> >>>>> Why can't the callee just check it? If it's None, just raise an >>>>> exception like usual? >>>> >>>> It's just that there's a lot more potential for rather easy optimization if >>>> the caller does it. >>> >>> Exactly. The NoneCheckNode is easy to get rid of at any stage in the >>> pipeline, whereas a hard coded None check has a fixed cost at runtime. >> >> I see, yes. I expect a pointer comparison to be reasonably >> insignificant compared to function call overhead, but it would also >> reduce the code in the instruction cache. If you take the address of >> the function though, or if you declare it public in a pxd, you >> probably don't want to do that, as you still want to be safe when >> called from C. Could do the same trick as in the 'less annotations' >> CEP though, that would be nice. > > ... or you could document that 'not None' means the caller cannot pass > it in, but that would be weird as you could do it from Cython and get > an exception, but not from C :) That would be better specified in the > documentation of the function as its contract or whatever.
"not None" on a cdef function means what all declarations on cdef functions mean: the caller is responsible for doing the appropriate type conversions and checks. If a function accepts an int32 and the caller puts a float32 on the stack, it's not the fault of the callee. The same applies to extension type arguments and None checks. Stefan _______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
