Re: Pythonification of the asterisk-based collection packing/unpacking syntax

References	(9 earlier) <457ebc8f-bb87-4005-b527-2fe6c02250c8@m7g2000vbc.googlegroups.com> <mailman.4078.1324830189.27778.python-list@python.org> <14c228af-0de5-448f-b617-832173aa6cba@p4g2000vbt.googlegroups.com> <mailman.4110.1324933521.27778.python-list@python.org> <82fd3bec-5afa-4e87-ae9a-8f93ecb9e366@dp8g2000vbb.googlegroups.com>
Date	2011-12-27 09:37 +1100
Subject	Re: Pythonification of the asterisk-based collection packing/unpacking syntax
From	Chris Angelico <rosuav@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.4113.1324939029.27778.python-list@python.org> (permalink)

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On Tue, Dec 27, 2011 at 9:12 AM, Eelco <hoogendoorn.eelco@gmail.com> wrote:
> On Dec 26, 10:05 pm, Chris Angelico <ros...@gmail.com> wrote:
>> A constraint can be applied at compile time or at run time. It'd be
>> valid to apply them at edit time, if you so chose - your editor could
>> refuse to save your file until you fix the problem. Doesn't mean a
>> thing.
>
> A constraint in the sense that I have explained many times now, can in
> no way, shape or form be applied at run time. Youd have better luck
> applying a consternation to a squirrel. Perhaps you meant 'type check'
> again? But then again, that makes no sense whatsoever at compile-
> time... Im starting to doubt if there is any sense to be found here at
> all.

A constraint failure causes an error at the time it's discovered.
1) Your editor pops up a message the instant you type something with
such an error, and forces you to correct it before going on.
2) Your compiler refuses to produce byte-code for the module.
3) When the line of code is executed, an exception is thrown.
All of these are valid ways of handling a constraint. Here is a Python
example of a type constraint:

def foo(arg):
    if not isinstance(arg,list): raise "This won't work."

If you call it with something that's not a list, you get an error.
Call it with a list, and execution continues normally. That's a
constraint. Of course, it might not be a _type_ constraint:

def foo(arg):
   if arg>5: raise "This won't work either." # and yes, that's oddly
truer in Python 3

(Aside: In Pike, I can actually put that into a type constraint
(declare the argument to be int(5..) for instance). This, however, is
not germane to the conversation.)

> Anyway, ill take your further silence on the matter as a 'sorry I
> derailed your thread with my confusion of terminology'

Like Mary Poppins, I never apologize for derailing threads :)

>> Python, by its nature, cannot do compile-time type checking.
>
> Python can do whatever its designers have put into it. In this case,
> that includes the emission of different code based on a (type)
> annotation at the point of declaration of an identifier (only in the
> particular circumstance of collection unpacking though, as far as I am
> aware).

Of course, but how can Python, without a completely different
structure, do compile-time checking of object types? Everything can be
monkey-patched at run-time. Anything could be affected by any function
call. It's impossible to say for certain, at compile time, what data
type anything will have.

ChrisA

Thread

Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-17 06:38 -0800
  Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-17 17:00 +0000
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Roy Smith <roy@panix.com> - 2011-12-17 12:14 -0500
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-18 04:18 +1100
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-17 12:11 -0800
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-17 23:20 +0000
  Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-18 00:59 +0000
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-18 13:45 +1100
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-18 03:33 +0000
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Roy Smith <roy@panix.com> - 2011-12-17 22:59 -0500
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-18 15:05 +1100
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Evan Driscoll <edriscoll@wisc.edu> - 2011-12-17 21:03 -0600
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-18 08:46 +0000
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Evan Driscoll <edriscoll@wisc.edu> - 2011-12-17 21:08 -0600
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-18 14:42 +1100
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Evan Driscoll <edriscoll@wisc.edu> - 2011-12-17 22:43 -0600
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-18 16:00 +1100
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-18 06:13 -0800
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-18 17:03 +0000
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-18 09:40 -0800
  Re: Pythonification of the asterisk-based collection packing/unpacking syntax buck <workitharder@gmail.com> - 2011-12-17 20:52 -0800
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-18 16:21 +1100
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Evan Driscoll <edriscoll@wisc.edu> - 2011-12-17 23:33 -0600
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-18 07:31 +0000
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-18 19:43 +1100
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax Roy Smith <roy@panix.com> - 2011-12-18 08:58 -0500
            Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-19 01:06 +1100
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Evan Driscoll <edriscoll@wisc.edu> - 2011-12-18 13:56 -0600
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax Duncan Booth <duncan.booth@invalid.invalid> - 2011-12-19 15:23 +0000
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-18 08:36 +0000
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Evan Driscoll <edriscoll@wisc.edu> - 2011-12-18 13:47 -0600
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-19 01:26 +0000
            Re: Pythonification of the asterisk-based collection packing/unpacking syntax Rick Johnson <rantingrickjohnson@gmail.com> - 2011-12-18 18:16 -0800
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax Andrew Berg <bahamutzero8825@gmail.com> - 2011-12-19 15:57 -0600
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Roy Smith <roy@panix.com> - 2011-12-19 19:30 -0500
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Andrew Berg <bahamutzero8825@gmail.com> - 2011-12-19 19:41 -0600
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax alex23 <wuwei23@gmail.com> - 2011-12-19 19:38 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Andrew Berg <bahamutzero8825@gmail.com> - 2011-12-19 22:04 -0600
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-20 20:51 +0000
            Re: Pythonification of the asterisk-based collection packing/unpacking syntax Ian Kelly <ian.g.kelly@gmail.com> - 2011-12-18 20:00 -0700
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-19 03:36 +0000
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-18 06:35 -0800
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Evan Driscoll <edriscoll@wisc.edu> - 2011-12-18 14:20 -0600
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax alex23 <wuwei23@gmail.com> - 2011-12-18 18:23 -0800
            Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-19 15:35 +1100
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax alex23 <wuwei23@gmail.com> - 2011-12-19 19:31 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-20 15:10 +1100
            Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-19 02:15 -0800
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax alex23 <wuwei23@gmail.com> - 2011-12-19 19:30 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-24 06:39 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax alex23 <wuwei23@gmail.com> - 2011-12-24 16:24 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Rick Johnson <rantingrickjohnson@gmail.com> - 2011-12-24 17:01 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-25 06:45 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-25 13:12 +0000
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-25 07:38 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-26 03:23 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-26 12:58 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-27 08:05 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-26 14:12 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-27 09:37 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-25 17:05 +0000
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-26 13:41 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-27 22:57 +0000
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-28 03:57 -0800
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Rick Johnson <rantingrickjohnson@gmail.com> - 2011-12-18 17:04 -0800
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Rick Johnson <rantingrickjohnson@gmail.com> - 2011-12-18 16:59 -0800
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-19 02:20 -0800
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax alex23 <wuwei23@gmail.com> - 2011-12-19 19:35 -0800
            Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-20 05:47 +0000
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax alex23 <wuwei23@gmail.com> - 2011-12-19 22:39 -0800
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax Serhiy Storchaka <storchaka@gmail.com> - 2011-12-20 11:58 +0200
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-24 06:45 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-25 02:01 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-24 09:23 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-25 04:51 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-25 12:50 +0000
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-25 06:59 -0800
            Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-24 06:41 -0800
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax Neal Becker <ndbecker2@gmail.com> - 2011-12-21 10:48 -0500
            Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-24 06:47 -0800
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-25 01:57 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-24 09:21 -0800
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-25 13:13 +0000
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-25 07:47 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-27 23:10 +0000
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Rick Johnson <rantingrickjohnson@gmail.com> - 2011-12-27 17:11 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-28 04:05 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-28 15:06 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-28 06:25 +0000
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-28 18:08 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-28 04:08 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Lie Ryan <lie.1296@gmail.com> - 2011-12-29 09:29 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-29 03:55 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-29 13:23 +0000
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-29 06:20 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Lie Ryan <lie.1296@gmail.com> - 2011-12-30 10:24 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-30 10:30 +1100
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax Ethan Furman <ethan@stoneleaf.us> - 2011-12-21 08:33 -0800
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Evan Driscoll <edriscoll@wisc.edu> - 2011-12-17 23:54 -0600
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-18 06:23 -0800
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Rick Johnson <rantingrickjohnson@gmail.com> - 2011-12-18 16:57 -0800
  Re: Pythonification of the asterisk-based collection packing/unpacking syntax Neal Becker <ndbecker2@gmail.com> - 2011-12-22 06:49 -0500
    Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-22 13:12 +0000
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-23 00:30 +1100
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Hans Mulder <hansmu@xs4all.nl> - 2011-12-22 15:13 +0100
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-23 01:30 +1100
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax Mel Wilson <mwilson@the-wire.com> - 2011-12-22 10:06 -0500
      Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-24 06:54 -0800
        Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-25 12:45 +0000
          Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-25 06:55 -0800
            Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-25 16:15 +0000
              Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-26 12:39 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-27 08:01 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-26 13:51 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-27 09:27 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-26 15:44 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Chris Angelico <rosuav@gmail.com> - 2011-12-27 11:52 +1100
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-27 02:01 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax alex23 <wuwei23@gmail.com> - 2012-01-02 18:38 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Rick Johnson <rantingrickjohnson@gmail.com> - 2012-01-02 21:39 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax alex23 <wuwei23@gmail.com> - 2012-01-02 23:01 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2012-01-03 03:21 -0800
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-27 23:07 +0000
                Re: Pythonification of the asterisk-based collection packing/unpacking syntax Eelco <hoogendoorn.eelco@gmail.com> - 2011-12-28 04:04 -0800

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