Re: def init(self):

From	Chris Angelico <rosuav@gmail.com>
Newsgroups	comp.lang.python
Subject	Re: def __init__(self):
Date	2016-04-27 03:30 +1000
Message-ID	<mailman.121.1461691805.32212.python-list@python.org> (permalink)
References	(8 earlier) <571f9836$0$1619$c3e8da3$5496439d@news.astraweb.com> <CALvWhxtRM+Qd983o2eB2SC4Hk0EsU26t-zbOQFW23a27Z3gx3Q@mail.gmail.com> <CAPTjJmoaJWHaXz_6jVoGzCm9Y4C+b5a=4C8gHoxt9B=jxQpJGQ@mail.gmail.com> <CALvWhxs4wk0c=PQrB7E6+KVQ5=mgo2At7HSP3_5v39t1jgeprw@mail.gmail.com> <CAPTjJmq2MxpR3VZPi5H-4Y6VAXy=1Jcfo7u0x2O2sP7uyzsDMQ@mail.gmail.com>

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On Wed, Apr 27, 2016 at 3:13 AM, Chris Kaynor <ckaynor@zindagigames.com> wrote:
> Yah, if you really wanted to make it work properly, you'd need to incref
> the newValue, while decref the oldValue. The incref would not be that
> difficult, but the decref would be more challenging, as you may have to
> also destroy the old object, though that might be possible by casting it
> back to a python object without the incref,. One way or the other, I did
> not exactly spend a ton of time to make it work properly :)

Exactly. :) Actually, the easiest fix is probably this:

import ctypes
def low_change_tuple(tuple, index, newValue):
    obj = ctypes.cast(id(tuple), ctypes.POINTER(ctypes.c_long))
    obj[3+index] = id(newValue)

def change_tuple(tup, idx, val):
    dummy = (val,)
    low_change_tuple(dummy, 0, tup[idx])
    low_change_tuple(tup, idx, val)

Refcounts are handled by the switch.

ChrisA

Thread

def __init__(self): San <santanu01@gmail.com> - 2016-04-25 23:21 -0700
  Re: def __init__(self): Ben Finney <ben+python@benfinney.id.au> - 2016-04-26 16:31 +1000
  Re: def __init__(self): Gary Herron <gherron@digipen.edu> - 2016-04-26 00:06 -0700
  Re: def __init__(self): Ben Finney <ben+python@benfinney.id.au> - 2016-04-26 17:34 +1000
    Re: def __init__(self): Marko Rauhamaa <marko@pacujo.net> - 2016-04-26 11:25 +0300
      Re: def __init__(self): Steven D'Aprano <steve@pearwood.info> - 2016-04-27 02:12 +1000
        Re: def __init__(self): Random832 <random832@fastmail.com> - 2016-04-26 12:26 -0400
          Re: def __init__(self): Steven D'Aprano <steve@pearwood.info> - 2016-04-27 02:32 +1000
            Re: def __init__(self): Chris Kaynor <ckaynor@zindagigames.com> - 2016-04-26 09:59 -0700
              Re: def __init__(self): Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-04-27 14:54 +1000
            Re: def __init__(self): Chris Angelico <rosuav@gmail.com> - 2016-04-27 03:04 +1000
            Re: def __init__(self): Chris Kaynor <ckaynor@zindagigames.com> - 2016-04-26 10:13 -0700
            Re: def __init__(self): Ian Kelly <ian.g.kelly@gmail.com> - 2016-04-26 11:26 -0600
            Re: def __init__(self): Chris Angelico <rosuav@gmail.com> - 2016-04-27 03:30 +1000
        Re: def __init__(self): Marko Rauhamaa <marko@pacujo.net> - 2016-04-26 19:38 +0300
  Re: def __init__(self): Random832 <random832@fastmail.com> - 2016-04-26 09:49 -0400
  Re: def __init__(self): Gary Herron <gherron@digipen.edu> - 2016-04-26 07:25 -0700

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