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| From | Random832 <random832@fastmail.com> |
| Subject | Re: Terminology: “reference” versus “pointer” |
| Date | Sat, 12 Sep 2015 01:42:43 -0400 |
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Ben Finney <ben+python@benfinney.id.au> writes: > The reference value is inaccessible to the program, it can only be used > to get at the referenced object. That's like saying an integer is inaccessible since it can only be used to add/subtract/etc (list of all operations you can do with an integer). What does it mean to access something, if not to do some operation on it? Getting the referenced object is the operation you can do with it. >> > So in Python, we don't have pointers because we don't have access to >> > change or reassign them. >> >> Yes you do. That's _exactly what happens_ in an assignment statement - >> you are reassigning it to the address of another object. And that's >> something you *can't do* with references in C++. > > The operation you describe doesn't change the reference; it doesn't > mutate an existing value which can be compared with whatever value it > had before. Instead, it throws away one reference and replaces it with a > different one. So, if you have a list x, and assign a new value to x[0], it doesn't change the list, because you can't compare the list to the value the list had before? You're not making any sense. It's a value. Changing it and "throwing away and replacing with a different one" are the same thing. > That's significant, because unlike a mutable value you can never again > get at the old reference in the Python program. I don't understand what you mean by "can never again get at" it if you think you _can_ do it for mutable values. >> > You can't, for example, keep the old reference (there are no references >> > to references in Python), because they're not accessible as values in >> > themselves. Once you assign a different reference, the old one is gone >> > and can't be found again. >> >> You can keep it by copying it to somewhere. > > How do you propose to “copy” a reference in Python? Making a new > reference to the referenced object is not making a copy of the > reference. Yes it is. I don't know why you think it's not, so I can't even figure out how to respond to this.
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Re: Python handles globals badly. tdev@freenet.de - 2015-09-11 14:26 -0700
Re: Python handles globals badly. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-11 23:50 +0200
Re: Python handles globals badly. Michael Torrie <torriem@gmail.com> - 2015-09-11 18:01 -0600
Re: Python handles globals badly. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-12 07:22 +0200
Re: Python handles globals badly. MRAB <python@mrabarnett.plus.com> - 2015-09-12 18:05 +0100
Re: Python handles globals badly. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-13 14:04 +0200
Re: Python handles globals badly. Steven D'Aprano <steve@pearwood.info> - 2015-09-13 22:06 +1000
Re: Python handles globals badly. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-13 14:11 +0200
Re: Python handles globals badly. Ned Batchelder <ned@nedbatchelder.com> - 2015-09-13 05:17 -0700
Re: Python handles globals badly. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-15 05:36 +0200
Re: Python handles globals badly. Emile van Sebille <emile@fenx.com> - 2015-09-12 10:18 -0700
Re: Python handles globals badly. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-13 14:06 +0200
Re: Python handles globals badly. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-13 14:10 +0200
Re: Python handles globals badly. Michael Torrie <torriem@gmail.com> - 2015-09-12 20:32 -0600
Re: Python handles globals badly. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-13 14:05 +0200
Re: Python handles globals badly. random832@fastmail.us - 2015-09-11 20:11 -0400
Re: Python handles globals badly. Michael Torrie <torriem@gmail.com> - 2015-09-11 18:34 -0600
Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 03:57 +0100
Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 04:01 +0100
Re: Python handles globals badly. Random832 <random832@fastmail.com> - 2015-09-12 00:06 -0400
Re: Python handles globals badly. Random832 <random832@fastmail.com> - 2015-09-12 00:16 -0400
Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 05:17 +0100
Terminology: “reference” versus “pointer” (was: Python handles globals badly.) Ben Finney <ben+python@benfinney.id.au> - 2015-09-12 14:27 +1000
Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 05:34 +0100
Re: Python handles globals badly. Random832 <random832@fastmail.com> - 2015-09-12 00:34 -0400
Re: Terminology: “reference” versus “pointer” Random832 <random832@fastmail.com> - 2015-09-12 00:42 -0400
Re: Terminology: “reference” versus “pointer” Steven D'Aprano <steve@pearwood.info> - 2015-09-13 02:32 +1000
Re: Terminology: "reference" versus "pointer" Rustom Mody <rustompmody@gmail.com> - 2015-09-12 09:54 -0700
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-13 03:06 +1000
Re: Terminology: "reference" versus "pointer" Emile van Sebille <emile@fenx.com> - 2015-09-12 10:14 -0700
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-13 03:24 +1000
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-13 03:34 +1000
Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 05:45 +0100
Re: Terminology: “reference” versus “pointer” Ben Finney <ben+python@benfinney.id.au> - 2015-09-12 14:52 +1000
Re: Terminology: “reference” versus “pointer” Random832 <random832@fastmail.com> - 2015-09-12 01:03 -0400
Re: Terminology: “reference” versus “pointer” Steven D'Aprano <steve@pearwood.info> - 2015-09-13 02:50 +1000
Re: Terminology: "reference" versus "pointer" Rustom Mody <rustompmody@gmail.com> - 2015-09-12 10:04 -0700
Re: Python handles globals badly. Random832 <random832@fastmail.com> - 2015-09-12 01:07 -0400
Re: Terminology: “reference” versus “pointer” Ben Finney <ben+python@benfinney.id.au> - 2015-09-12 15:20 +1000
Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 06:25 +0100
Re: Python handles globals badly. Random832 <random832@fastmail.com> - 2015-09-12 01:35 -0400
Re: Terminology: “reference” versus “pointer” Random832 <random832@fastmail.com> - 2015-09-12 01:42 -0400
Re: Python handles globals badly. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 06:54 +0100
Re: Terminology: “reference” versus “pointer” Chris Angelico <rosuav@gmail.com> - 2015-09-12 16:02 +1000
Re: Terminology: “reference” versus “pointer” Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-12 07:05 +0100
Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-12 16:13 +1000
Re: Terminology: “reference” versus “pointer” Random832 <random832@fastmail.com> - 2015-09-12 02:15 -0400
Re: Python handles globals badly. Random832 <random832@fastmail.com> - 2015-09-12 02:25 -0400
Re: Terminology: “reference” versus “pointer” Ben Finney <ben+python@benfinney.id.au> - 2015-09-12 16:26 +1000
Re: Terminology: "reference" versus "pointer" Rustom Mody <rustompmody@gmail.com> - 2015-09-12 05:46 -0700
Re: Terminology: "reference" versus "pointer" Laura Creighton <lac@openend.se> - 2015-09-12 16:41 +0200
Re: Terminology: "reference" versus "pointer" Rustom Mody <rustompmody@gmail.com> - 2015-09-12 08:13 -0700
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-12 09:17 -0700
Re: Terminology: "reference" versus "pointer" Rustom Mody <rustompmody@gmail.com> - 2015-09-12 10:12 -0700
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-13 04:14 +1000
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-13 03:48 +1000
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-12 11:45 -0700
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-13 22:50 +1000
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-13 23:29 +1000
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-13 18:34 -0700
Re: Terminology: "reference" versus "pointer" Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-14 04:34 +0100
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-12 12:58 -0700
Re: Terminology: "reference" versus "pointer" Emile van Sebille <emile@fenx.com> - 2015-09-12 15:14 -0700
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-12 15:34 -0700
Re: Terminology: "reference" versus "pointer" Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-13 00:14 +0100
Re: Terminology: "reference" versus "pointer" Ned Batchelder <ned@nedbatchelder.com> - 2015-09-12 17:02 -0700
Re: Terminology: "reference" versus "pointer" Rustom Mody <rustompmody@gmail.com> - 2015-09-12 17:28 -0700
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-12 17:44 -0700
Re: Terminology: "reference" versus "pointer" Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-13 03:22 +0100
Re: Terminology: "reference" versus "pointer" Ned Batchelder <ned@nedbatchelder.com> - 2015-09-12 19:25 -0700
Re: Terminology: "reference" versus "pointer" Michael Torrie <torriem@gmail.com> - 2015-09-12 20:35 -0600
Re: Terminology: "reference" versus "pointer" Ben Finney <ben+python@benfinney.id.au> - 2015-09-13 12:42 +1000
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-13 08:31 -0700
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-14 01:39 +1000
Re: Terminology: "reference" versus "pointer" Ben Finney <ben+python@benfinney.id.au> - 2015-09-14 06:48 +1000
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-13 18:13 -0700
Re: Terminology: "reference" versus "pointer" Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-09-13 12:32 -0400
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-12 17:23 -0700
Re: Terminology: "reference" versus "pointer" Rustom Mody <rustompmody@gmail.com> - 2015-09-12 16:39 -0700
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-13 10:19 +1000
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-12 17:25 -0700
Re: Terminology: "reference" versus "pointer" rurpy@yahoo.com - 2015-09-12 18:07 -0700
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-12 20:54 +0300
Re: Terminology: "reference" versus "pointer" Rustom Mody <rustompmody@gmail.com> - 2015-09-12 11:21 -0700
Re: Terminology: "reference" versus "pointer" Jussi Piitulainen <harvesting@makes.email.invalid> - 2015-09-12 23:02 +0300
Re: Terminology: "reference" versus "pointer" Random832 <random832@fastmail.com> - 2015-09-12 17:10 -0400
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-13 12:30 +1000
Re: Terminology: "reference" versus "pointer" Jussi Piitulainen <harvesting@makes.email.invalid> - 2015-09-13 09:40 +0300
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-12 23:13 +0300
Re: Terminology: "reference" versus "pointer" Random832 <random832@fastmail.com> - 2015-09-12 17:27 -0400
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-13 21:04 +0300
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-14 05:03 +1000
Re: Terminology: "reference" versus "pointer" Random832 <random832@fastmail.com> - 2015-09-13 15:04 -0400
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 02:17 +0300
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-14 11:10 +1000
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 04:22 +0300
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-14 12:38 +1000
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 06:23 +0300
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-15 02:59 +1000
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 20:24 +0300
Re: Terminology: "reference" versus "pointer" Ned Batchelder <ned@nedbatchelder.com> - 2015-09-14 11:29 -0700
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 22:30 +0300
Re: Terminology: "reference" versus "pointer" Ned Batchelder <ned@nedbatchelder.com> - 2015-09-14 13:16 -0700
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 23:32 +0300
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-14 11:30 +1000
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 05:26 +0300
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-14 09:52 +1000
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 03:30 +0300
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-14 10:58 +1000
Re: Terminology: "reference" versus "pointer" Random832 <random832@fastmail.com> - 2015-09-13 19:38 -0400
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 17:48 +0300
Re: Terminology: "reference" versus "pointer" Random832 <random832@fastmail.com> - 2015-09-14 11:10 -0400
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-15 03:03 +1000
Re: Terminology: "reference" versus "pointer" Random832 <random832@fastmail.com> - 2015-09-14 13:34 -0400
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-16 00:26 +1000
Re: Terminology: "reference" versus "pointer" Emile van Sebille <emile@fenx.com> - 2015-09-14 10:51 -0700
Re: Terminology: "reference" versus "pointer" Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-09-16 20:14 +1200
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-16 18:18 +1000
Re: Terminology: "reference" versus "pointer" Ben Finney <ben+python@benfinney.id.au> - 2015-09-16 18:24 +1000
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-16 18:33 +1000
Re: Terminology: "reference" versus "pointer" Chris Angelico <rosuav@gmail.com> - 2015-09-15 03:59 +1000
Re: Terminology: "reference" versus "pointer" Random832 <random832@fastmail.com> - 2015-09-14 14:02 -0400
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-16 00:14 +1000
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 20:45 +0300
Re: Terminology: "reference" versus "pointer" Random832 <random832@fastmail.com> - 2015-09-14 14:00 -0400
Re: Terminology: "reference" versus "pointer" Akira Li <4kir4.1i@gmail.com> - 2015-09-14 21:17 +0300
Re: Terminology: "reference" versus "pointer" Steven D'Aprano <steve@pearwood.info> - 2015-09-13 03:08 +1000
Re: Terminology: "reference" versus "pointer" Rustom Mody <rustompmody@gmail.com> - 2015-09-12 10:26 -0700
Re: Terminology: "reference" versus "pointer" Ben Finney <ben+python@benfinney.id.au> - 2015-09-13 11:13 +1000
Re: Python handles globals badly. Chris Angelico <rosuav@gmail.com> - 2015-09-12 16:27 +1000
Re: Terminology: “reference” versus “pointer” Chris Angelico <rosuav@gmail.com> - 2015-09-12 16:31 +1000
Re: Python handles globals badly. Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-11 16:10 -0600
Re: Python handles globals badly. MRAB <python@mrabarnett.plus.com> - 2015-09-12 00:03 +0100
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