Iterator support in Cython.

gistfile1.md

To make extension iterable you define iter on it.

cdef class I:

   cdef:

   list data

   int i

   def __init__(self):

   self.data = range(100)

   self.i = 0

   def __iter__(self):

   return self

   def __next__(self):

   if self.i >= len(self.data):

   raise StopIteration()

   ret = self.data[self.i]

   self.i += 1

   return ret

It can be used in for loops.

In [3]: i = I()

 

In [4]: s = 0

 

In [5]: for x in i:

  ...: s += x

  ...:

 

In [6]: s

Out[6]: 4950

Instances can be used where iterator is required.

In [15]: it = iter(I())

 

In [16]: it.next()

Out[16]: 0

 

In [17]: next(it)

Out[17]: 1