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| References | <51d4eb9c$0$29999$c3e8da3$5496439d@news.astraweb.com> <mailman.4200.1372910878.3114.python-list@python.org> <51d508ed$0$6512$c3e8da3$5496439d@news.astraweb.com> |
|---|---|
| From | Ian Kelly <ian.g.kelly@gmail.com> |
| Date | 2013-07-04 01:12 -0600 |
| Subject | Re: Default scope of variables |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.4210.1372921992.3114.python-list@python.org> (permalink) |
On Wed, Jul 3, 2013 at 11:32 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
>> Python lets you do that across but not within functions.
>>
>> But Javascript/ECMAScript/whatever doesn't give you that. A var
>> declaration makes it function-local, no matter where the declaration is.
>> That's pointless. C++, on the other hand, lets you do this:
>>
>> void somefunc() {
>> for (int i=0;i<10;++i) {
>> // do something with outer i
>> for (int i=0;i<4;++i) {
>> // do something with inner i
>> }
>> // outer i is visible again
>> }
>> // neither i is visible
>> }
>
> That's truly horrible. If the cost of this "flexibility" is that I'll
> have to read, and debug, other people's code with this sort of thing, I'm
> happy to be less flexible. For what possible reason other than "because I
> can" would you want to use the same loop variable name in two nested
> loops?
It's interesting to note that while Java and C# also allow reuse of
local variable names, they do not allow local variables declared in
inner scopes to shadow variables declared in enclosing scopes, as in
the example above. But the following would be perfectly legal:
void somefunc() {
for (int i = 0; i < a.size; ++i) {
// do something with a[i]
}
for (int i = 0; i < b.size; ++i) {
// do something with b[i]
}
}
And the two i's are treated as completely separate variables here, as
arguably they should be since they're used for two distinct purposes.
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Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-04 03:27 +0000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-04 14:07 +1000
Re: Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-04 05:32 +0000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-04 15:47 +1000
Re: Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-04 16:38 +0000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-05 02:58 +1000
Re: Default scope of variables Wayne Werner <wayne@waynewerner.com> - 2013-07-07 08:13 -0500
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-07 23:43 +1000
Re: Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-07 16:03 +0000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-08 10:46 +1000
Re: Default scope of variables alex23 <wuwei23@gmail.com> - 2013-07-09 14:52 +1000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-09 15:07 +1000
Re: Default scope of variables alex23 <wuwei23@gmail.com> - 2013-07-09 16:08 +1000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-09 16:13 +1000
Re: Default scope of variables "Frank Millman" <frank@chagford.com> - 2013-07-09 09:35 +0200
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-09 17:45 +1000
Re: Default scope of variables Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-09 01:56 -0600
Re: Default scope of variables "Frank Millman" <frank@chagford.com> - 2013-07-09 10:22 +0200
Re: Default scope of variables "Frank Millman" <frank@chagford.com> - 2013-07-09 10:38 +0200
Re: Default scope of variables Ethan Furman <ethan@stoneleaf.us> - 2013-07-09 09:07 -0700
Re: Default scope of variables Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-09 10:44 -0600
Re: Default scope of variables Ethan Furman <ethan@stoneleaf.us> - 2013-07-09 10:23 -0700
Re: Default scope of variables Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-09 12:41 -0600
Re: Default scope of variables Ethan Furman <ethan@stoneleaf.us> - 2013-07-09 12:19 -0700
Re: Default scope of variables "Frank Millman" <frank@chagford.com> - 2013-07-10 07:54 +0200
Re: Default scope of variables Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-10 09:42 -0600
Re: Default scope of variables Ethan Furman <ethan@stoneleaf.us> - 2013-07-10 08:29 -0700
Re: Default scope of variables "Frank Millman" <frank@chagford.com> - 2013-07-11 07:52 +0200
Re: Default scope of variables Ethan Furman <ethan@stoneleaf.us> - 2013-07-07 09:52 -0700
Re: Default scope of variables Ethan Furman <ethan@stoneleaf.us> - 2013-07-07 11:59 -0700
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-08 10:48 +1000
Re: Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-08 02:23 +0000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-08 13:11 +1000
Re: Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-08 05:00 +0000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-08 15:14 +1000
Re: Default scope of variables Peter Otten <__peter__@web.de> - 2013-07-04 08:48 +0200
Re: Default scope of variables Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-04 01:12 -0600
Re: Default scope of variables Dave Angel <davea@davea.name> - 2013-07-04 03:06 -0400
Re: Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-04 15:52 +0000
Re: Default scope of variables Rotwang <sg552@hotmail.co.uk> - 2013-07-04 17:54 +0100
Re: Default scope of variables Peter Otten <__peter__@web.de> - 2013-07-04 20:36 +0200
Re: Default scope of variables Joshua Landau <joshua.landau.ws@gmail.com> - 2013-07-05 01:04 +0100
Re: Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-05 01:24 +0000
Re: Default scope of variables Dave Angel <davea@davea.name> - 2013-07-04 22:03 -0400
Re: Default scope of variables Joshua Landau <joshua.landau.ws@gmail.com> - 2013-07-05 03:29 +0100
Re: Default scope of variables Joshua Landau <joshua.landau.ws@gmail.com> - 2013-07-05 03:27 +0100
Re: Default scope of variables Rotwang <sg552@hotmail.co.uk> - 2013-07-05 07:28 +0100
Re: Default scope of variables Neil Cerutti <neilc@norwich.edu> - 2013-07-05 13:24 +0000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-05 23:43 +1000
Re: Default scope of variables Neil Cerutti <neilc@norwich.edu> - 2013-07-05 15:36 +0000
Re: Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-07 16:08 +0000
Re: Default scope of variables Neil Cerutti <neilc@norwich.edu> - 2013-07-08 11:54 +0000
Re: Default scope of variables Joshua Landau <joshua.landau.ws@gmail.com> - 2013-07-08 14:14 +0100
Re: Default scope of variables Lele Gaifax <lele@metapensiero.it> - 2013-07-04 14:43 +0200
Re: Default scope of variables Wayne Werner <wayne@waynewerner.com> - 2013-07-04 10:45 -0500
Re: Default scope of variables Joshua Landau <joshua.landau.ws@gmail.com> - 2013-07-04 05:30 +0100
Re: Default scope of variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-04 05:45 +0000
Re: Default scope of variables Chris Angelico <rosuav@gmail.com> - 2013-07-04 14:36 +1000
Re: Default scope of variables Joshua Landau <joshua.landau.ws@gmail.com> - 2013-07-04 06:09 +0100
Re: Default scope of variables Joshua Landau <joshua.landau.ws@gmail.com> - 2013-07-08 17:58 +0100
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