Re: Design thought for callbacks

From	Marko Rauhamaa <marko@pacujo.net>
Newsgroups	comp.lang.python
Subject	Re: Design thought for callbacks
Date	2015-02-22 11:14 +0200
Organization	A noiseless patient Spider
Message-ID	<87ioeui9zd.fsf@elektro.pacujo.net> (permalink)
References	(5 earlier) <54e9391b$0$13010$c3e8da3$5496439d@news.astraweb.com> <87r3tiids7.fsf@elektro.pacujo.net> <mailman.18989.1424593399.18130.python-list@python.org> <87mw46ibtq.fsf@elektro.pacujo.net> <mailman.18990.1424595520.18130.python-list@python.org>

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Chris Angelico <rosuav@gmail.com>:

> On Sun, Feb 22, 2015 at 7:34 PM, Marko Rauhamaa <marko@pacujo.net> wrote:
>> Refloops are not to be worried about, let alone removed.
>
> Why?

Because the whole point of GC-languages is that you should stop worrying
about memory. Trying to mastermind and micromanage GC in the application
is, pardon my French, an antipattern.

> They force the use of the much slower cycle-detecting GC, rather than
> the quick and efficient CPython refcounter.

Java's Hotspot doesn't bother with refcounters but is much faster than
Python. CPython's refcounters are a historical accident that a Python
application developer shouldn't even be aware of.

> I don't know how other Pythons work, but mark-and-sweep has its own
> costs, and I don't know of any system that's both prompt and able to
> detect refloops.

It's exceedingly difficult (and pointless) to detect cycles in your
object structures. Python is going to have to do a GC occasionally
anyway. Yes, your worst-case response times are going to suffer, but
that's the cost of doing business.

> Helping it along means your program doesn't waste memory. Why such a
> blanket statement?

Because worrying Python programmers with evil spirits (reference loops)
leads to awkward coding practices and takes away one of the main
advantages of Python as a high-level programming language.

Marko

Thread

Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-21 08:13 -0500
  Re: Design thought for callbacks Grant Edwards <invalid@invalid.invalid> - 2015-02-21 20:57 +0000
    Re: Design thought for callbacks Marko Rauhamaa <marko@pacujo.net> - 2015-02-21 23:57 +0200
      Re: Design thought for callbacks Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-22 13:04 +1100
        Re: Design thought for callbacks Chris Angelico <rosuav@gmail.com> - 2015-02-22 13:11 +1100
          Re: Design thought for callbacks Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-22 15:38 +1100
            Re: Design thought for callbacks Chris Angelico <rosuav@gmail.com> - 2015-02-22 17:21 +1100
              Re: Design thought for callbacks Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-22 21:32 +1100
                Re: Design thought for callbacks Chris Angelico <rosuav@gmail.com> - 2015-02-22 22:14 +1100
                Re: Design thought for callbacks Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-23 00:45 +1100
                Re: Design thought for callbacks Chris Angelico <rosuav@gmail.com> - 2015-02-23 01:01 +1100
        Re: Design thought for callbacks Marko Rauhamaa <marko@pacujo.net> - 2015-02-22 09:52 +0200
          Re: Design thought for callbacks Chris Angelico <rosuav@gmail.com> - 2015-02-22 19:17 +1100
            Re: Design thought for callbacks Marko Rauhamaa <marko@pacujo.net> - 2015-02-22 10:34 +0200
              Re: Design thought for callbacks Chris Angelico <rosuav@gmail.com> - 2015-02-22 19:58 +1100
                Re: Design thought for callbacks Marko Rauhamaa <marko@pacujo.net> - 2015-02-22 11:14 +0200
                Re: Design thought for callbacks Chris Angelico <rosuav@gmail.com> - 2015-02-22 21:21 +1100
                Re: Design thought for callbacks Laura Creighton <lac@openend.se> - 2015-02-22 12:28 +0100
                Re: Design thought for callbacks Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-23 00:57 +1100
                Re: Design thought for callbacks Marko Rauhamaa <marko@pacujo.net> - 2015-02-22 16:06 +0200
    Re: Design thought for callbacks Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-22 00:05 -0700
    Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-22 08:21 -0500
      Re: Design thought for callbacks Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-02-24 18:20 +1300
        Re: Design thought for callbacks random832@fastmail.us - 2015-02-24 00:29 -0500
          Re: Design thought for callbacks Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-02-25 10:19 +1300
            Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-25 07:50 -0500
              Re: Design thought for callbacks Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-02-26 18:36 +1300
                Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-02-26 05:58 -0500
                Re: Design thought for callbacks Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-26 12:54 -0700
                Re: Design thought for callbacks Ethan Furman <ethan@stoneleaf.us> - 2015-02-26 12:00 -0800
                Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-03-02 06:06 -0500
                Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-03-02 06:04 -0500
                Re: Design thought for callbacks Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-02 08:34 -0700
                Re: Design thought for callbacks Cem Karan <cfkaran2@gmail.com> - 2015-03-08 14:30 -0400

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