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Re: Assignment Versus Equality

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From Christopher Reimer <christopher_reimer@icloud.com>
Newsgroups comp.lang.python
Subject Re: Assignment Versus Equality
Date Sun, 26 Jun 2016 11:47:25 -0700
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On 6/26/2016 6:21 AM, Steven D'Aprano wrote:

> On Sun, 26 Jun 2016 08:48 pm, BartC wrote:
>
>> On 26/06/2016 08:36, Lawrence D’Oliveiro wrote:
>>> One of Python’s few mistakes was that it copied the C convention of using
>>> “=” for assignment and “==” for equality comparison.
>> One of C's many mistakes. Unfortunately C has been very influential.
>>
>> However, why couldn't Python have used "=" both for assignment, and for
>> equality? Since I understand assignment ops can't appear in expressions.
> Personally, I think that even if there is no *syntactical* ambiguity between
> assignment and equality, programming languages should still use different
> operators for them. I must admit that my first love is still Pascal's :=
> for assignment and = for equality, but C's = for assignment and == for
> equality it *almost* as good.
>
> (It loses a mark because absolute beginners confuse the assignment = for the
> = in mathematics, which is just different enough to cause confusion.)
>
> But the BASIC style = for both assignment and equality is just begging for
> confusion. Even though = is not ambiguous given BASIC's rules, it can still
> be ambiguous to beginners who haven't yet digested those rules and made
> them second nature.
>
> And even experts don't always work with complete statements. Here is a
> snippet of BASIC code:
>
> X = Y
>
> Is it an assignment or an equality comparison? Without seeing the context,
> it is impossible to tell:
>
> 10 X = Y + 1
> 20 IF X = Y GOTO 50
>
>
> Now obviously BASIC was a very popular and successful language, for many
> years, despite that flaw. But I wouldn't repeat it in a new language.
>
>
>>> It should have copied the old convention from Algol-like languages
>>> (including Pascal), where “:=” was assignment, so “=” could keep a
>>> meaning closer to its mathematical usage.
>> (I think Fortran and PL/I also used "=" for assignment. Both were more
>> commercially successful than Algol or Pascal.)
> Fortran 77 used .EQ. for equality. I'm not sure about PL/I.
>
> I'm also not sure I'd agree about the commercial success. Fortran certainly
> has been extremely popular, albeit almost entirely in numerical computing.
> But PL/I has virtually disappeared from the face of the earth, while Pascal
> still has a small but dedicated community based on FreePascal, GNU Pascal,
> and Delphi.
>
> (Of the three, FreePascal and Delphi appear to still be getting regular
> releases.)

I started writing a BASIC interpreter in Python. The rudimentary version 
for 10 PRINT "HELLO, WORLD!" and 20 GOTO 10 ran well. The next version 
to read each line into a tree structure left me feeling over my head. So 
I got "Writing Compilers & Interpreters: An Applied Approach" by Ronald 
Mak (1991 edition) from Amazon, which uses C for coding and Pascal as 
the target language.  I know a little bit of C and nothing of Pascal. 
Translating an old dialect of C into modern C, learning Pascal and 
figuring out the vagaries of BASIC should make for an interesting 
learning experience.

Chris R.

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Thread

Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-26 00:36 -0700
  Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-26 11:48 +0100
    Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-26 23:21 +1000
      Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-26 07:26 -0700
        Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-26 11:31 -0400
      Re: Assignment Versus Equality Christopher Reimer <christopher_reimer@icloud.com> - 2016-06-26 11:47 -0700
      Re: Assignment Versus Equality Michael Torrie <torriem@gmail.com> - 2016-06-26 15:28 -0600
      Re: Assignment Versus Equality Bob Gailer <bgailer@gmail.com> - 2016-06-27 08:22 -0400
        Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 05:48 -0700
          Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-27 23:28 +1000
            Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-27 16:58 +0300
            Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 07:23 -0700
              Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-28 11:05 +1000
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 21:31 -0700
                Re: Assignment Versus Equality Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-28 15:42 +1000
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-28 16:04 +1000
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 09:12 +0300
                Re: Assignment Versus Equality Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-06-28 11:04 +0300
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 23:09 -0700
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 00:12 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-28 17:26 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 01:49 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-28 20:34 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 17:42 -0700
                Re: Assignment Versus Equality Random832 <random832@fastmail.com> - 2016-06-28 10:13 -0400
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 19:39 +0300
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 19:41 +0300
                Re: Assignment Versus Equality Random832 <random832@fastmail.com> - 2016-06-28 13:19 -0400
                Re: Assignment Versus Equality Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-28 12:27 -0600
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 22:40 +0300
                Re: Assignment Versus Equality Gene Heskett <gheskett@shentel.net> - 2016-06-28 16:59 -0400
                Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-30 12:29 +1200
                Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-30 12:50 +1000
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-30 09:22 +0300
                Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-29 12:27 +1000
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 20:52 -0700
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 21:03 -0700
                Re: Assignment Versus Equality Random832 <random832@fastmail.com> - 2016-06-29 00:52 -0400
              Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-27 18:14 -0700
            Re: Assignment Versus Equality Gene Heskett <gheskett@shentel.net> - 2016-06-27 11:21 -0400
          Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-27 20:04 -0400
    Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-26 11:21 -0400
      Re: Assignment Versus Equality Cousin Stanley <HooDunnit@didly42KahZidly.net> - 2016-06-26 08:47 -0700
        Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-26 16:56 +0100
          Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-27 11:38 +1200
          Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-27 07:30 -0400
            Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-28 18:17 +1200
          Re: Assignment Versus Equality Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-27 13:59 +0000
            Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-27 17:09 +0300
              Re: Assignment Versus Equality sohcahtoa82@gmail.com - 2016-06-27 17:33 -0700
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 07:25 +0300
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 23:54 -0700
            Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 07:10 -0700
              Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-29 12:35 +1000
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 14:19 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 21:51 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 15:07 +1000
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 22:55 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 16:26 +1000
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 23:33 -0700
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 23:37 -0700
                Re: Assignment Versus Equality Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-29 15:26 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 22:51 -0700
                Re: Assignment Versus Equality Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-29 16:45 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-29 01:07 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 18:09 +1000
                Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-29 22:36 +1000
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-29 14:24 +0100
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 23:35 +1000
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-29 15:47 +0100
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 23:34 +1000
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-29 10:49 +0100
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-29 02:56 -0700
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-29 11:10 +0100
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-29 03:24 -0700
            Re: Assignment Versus Equality Alain Ketterlin <alain@universite-de-strasbourg.fr.invalid> - 2016-06-27 16:48 +0200
              Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 22:00 -0700
            Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-28 11:34 +1000
          Re: Assignment Versus Equality MRAB <python@mrabarnett.plus.com> - 2016-06-27 16:27 +0100
            Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-27 14:56 -0700
            Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-27 15:45 -0700
              Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-28 00:08 +0100
                Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-27 20:11 -0400
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-28 11:35 +0100
                Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-28 18:59 +1200
            Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-28 11:28 +1000
          Re: Assignment Versus Equality Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-27 15:42 +0000
      Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-26 19:11 +0300
    Re: Assignment Versus Equality MRAB <python@mrabarnett.plus.com> - 2016-06-26 16:41 +0100
      Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-26 17:08 +0100
    Re: Assignment Versus Equality Christopher Reimer <christopher_reimer@icloud.com> - 2016-06-26 11:53 -0700
      Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-27 11:41 +1200
    Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-27 11:22 +1200
      Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-27 00:39 +0100
        Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-28 18:15 +1200

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