generator/coroutine terminology

[Albert van der Horst]

In article <mailman.372.1427809109.10327.python-list at python.org>,
Dave Angel  <davea at davea.name> wrote:
>On 03/31/2015 09:18 AM, Albert van der Horst wrote:
>> In article <55062bda$0$12998$c3e8da3$5496439d at news.astraweb.com>,
>> Steven D'Aprano  <steve+comp.lang.python at pearwood.info> wrote:
>
>>>
>>> The biggest difference is syntactic. Here's an iterator which returns a
>>> never-ending sequence of squared numbers 1, 4, 9, 16, ...
>>>
>>> class Squares:
>>>     def __init__(self):
>>>         self.i = 0
>>>     def __next__(self):
>>>         self.i += 1
>>>         return self.i**2
>>>     def __iter__(self):
>>>         return self
>>
>> You should give an example of usage. As a newby I'm not up to
>> figuring out the specification from source for
>> something built of the mysterious __ internal
>> thingies.
>> (I did experiment with Squares interactively. But I didn't get
>> further than creating a Squares object.)
>>
>
>He did say it was an iterator.  So for a first try, write a for loop:
>
>class Squares:
>    def __init__(self):
>        self.i = 0
>    def __next__(self):
>        self.i += 1
>        return self.i**2
>    def __iter__(self):
>        return self
>
>for i in Squares():
>     print(i)
>     if i > 50:
>         break
>

This is what I get:
/ --------------------------
albert at cherry:/tmp$ more aap.py
class Squares:
    def __init__(self):
        self.i = 0
    def __next__(self):
        self.i += 1
        return self.i**2
    def __iter__(self):
        return self

albert at cherry:/tmp$ python
Python 2.6.6 (r266:84292, Dec 26 2010, 22:31:48)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from aap import *
>>> for i in Squares():
...     print i
...     if i>50: break
...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: instance has no next() method
>>>

/ --------------------------

Probably not what is intended.

Last minute note:
   renaming __next__() into next() did the job.

>--
>DaveA

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst