[Pyrex] C-methods in extension types

[Helmut Jarausch]

Hi,
I'm new to Pyrex and I don't understand the difference
between a Python method (declared by 'def') and a
C method (declared by 'cdef')

My very first example was this little iterator test

cdef class IT:

  cdef int From
  cdef int To
  cdef int count
  cdef int Step
  
  def __new__(self,From,To,reversed=0):
    if reversed:
      self.Step= -1
      self.From= To+1
      self.To  = From
    else:
      self.Step= 1
      self.From= From-1
      self.To  = To
    
  
  def __iter__(self):
    self.count= self.From
    return self
  
  def __next__(self):
    if  self.count == self.To :
      raise StopIteration
#      return NULL   # signal STopIteration
    else :
      self.count= self.count + self.Step
      return self.count

which works just fine.
But when I try e.g.

  cdef __new__(self,int From,int To,int reversed):
    if reversed:
      self.Step= -1
      self.From= To+1
      self.To  = From
    else:
      self.Step= 1
      self.From= From-1
      self.To  = To

Then pyrexc doesn't cry but compiles invalid code:
the function which is put into the tp_new slot
calls the __new__ method with only 3 arguments
(which gcc doesn't like)

What am I missing?

Many thanks for a hint,

Helmut Jarausch

Lehrstuhl fuer Numerische Mathematik
RWTH - Aachen University
D 52056 Aachen, Germany