On Oct 3, 2008, at 3:35 AM, Dag Sverre Seljebotn wrote:
> Robert Bradshaw wrote:
>> On Oct 2, 2008, at 2:03 PM, Gabriel Gellner wrote:
>>
>>> On Thu, Oct 02, 2008 at 05:00:40PM -0400, Gabriel Gellner wrote:
>>>> is there any way to assign an cdef C array at assignment time?
>>>>
>>>> I want something like:
>>>>
>>>> cdef double a[4] = {0.5, 0.3, 0.1, 0.1}
>>>>
>>>> as anything like this possible in Cython? Or do I need to do
>>>> explicit
>>>> initialization.
>>>>
>>> And if it is explicit is there any way to not just do (can I do
>>> some kind of
>>> block assignment?)
>>>
>>> a[0] = 0.5
>>> ...
>>> a[3] = 0.1
>>>
>>> Looking for magic :-)
>>
>> Nothing yet, I put up http://trac.cython.org/cython_trac/ticket/93
>>
>> Also, I would like to be able to use (literal) tuples/dicts to assign
>> to structs (and vice-versa). Would non-literal tuples/dicts be going
>> too far?
>
> I think a default "literal struct constructor" might be more fitting?
> And I see no reason it would need to be literal except for brevity
> of C
> code.
The literalness may not be reflected in the code (though it could
impact more than the brevity of the C code, as assignment one-by-one
may involve literals in the assembly, as opposed to a memcpy to
assign an array at once.
> A problem is with mutability though, if it is done using C static
> allocation. I.e.:
>
> def f(x):
> cdef int a[3] = [1,2,3]
> if x: a[2] = 1
> print a[2]
>
> f(True) # prints 1...
> f(False) # likely prints 1 too!
>
> This is consistent with what you expect from C but very contrary to
> what
> Python users would expect.
No, I believe allocation is done on the stack.
- Robert
_______________________________________________
Cython-dev mailing list
[email protected]
http://codespeak.net/mailman/listinfo/cython-dev
