On 05/07/2012 06:18 PM, mark florisson wrote:
On 7 May 2012 17:16, mark florisson<markflorisso...@gmail.com> wrote:
On 7 May 2012 17:12, Stefan Behnel<stefan...@behnel.de> 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.
Stefan
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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.
We're going to need a "Cython ABI" at some point anyway. "Caller checks
for None" goes in the ABI docs.
Dag
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