On Sunday, September 29, 2013 9:21:03 AM UTC+1, Dima Pasechnik wrote:
> in the loop:
> cdef Integer accumulator = Integer(0)
> cdef vector[int].iterator i = self.data.begin()
> while i != self.data.end():
> mpz_add_ui(accumulator.value, accumulator.value, <int>(i[0]))
> i += 1
>
> which is not clear to me:
> 1) why can't one just use '+' instead? Is it a cython limitation?
>
Using + means calling accumulator.__add__() which will expect a python
object as argument. So you would have to wrap the increment *i first in a
Sage Integer. This can be done, of course, but is slightly slower.
> 2) why i[0] ?
>
In Cython, dereference is expressed using [0] and not with unary *
In other words C/C++
int *pointer = ...;
int x = *pointer;
becomes
cdef int *pointer = ...
cdef int x = pointer[0]
in Cython.
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