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From: Bart <bc@freeuk.com>
Newsgroups: comp.lang.c
Subject: Re: Top 10 most common hard skills listed on resumes...
Date: Fri, 6 Sep 2024 23:38:05 +0100
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On 06/09/2024 18:23, James Kuyper wrote:
> On Fri, 6 Sep 2024 10:35:16 +0100
> Bart <bc@freeuk.com> wrote:
> 
>> On 05/09/2024 22:37, James Kuyper wrote:
>>> On 9/5/24 12:54, Kaz Kylheku wrote:
> ...
>>>> Both sides of an assignment can be complex expressions that
>>>> designate an object (though the right side need not).
>>>
>>> So you've correctly identified the very fundamental asymmetry.
>>>    
>>
>> Sure, if you want to completely disregard all the cases where the
>> symmetry does exist.
> 
> Anything can be considered symmetric, if you ignore all the aspects of
> it that are asymmetric. As a result, calling something symmetric for
> that reason isn't worth commenting on.
> 
> A more useful way of describing what you're commenting on is not to
> falsely claim that assignment in general is symmetric, but rather that
> the particular assignment you're interest in is symmetric. And it's only
> symmetric syntactically; the associated semantics are profoundly asymmetric.

In every kind of assignment, a variable is denoted in the same way on 
either side of '=' if accessing its value (either to read or write). It 
has the same type. It has the amount of indirection.

The same applies to more elaborate terms: if it can appear on the LHS, 
it can appear unchanged on the RHS:

  A[i+1].m = x;
  y = A[i+1].m;

That A[i+1].m term can be written the same way on either side, but it 
doesn't need to be on both sides of the same assignment! That wouldn't 
be that useful.

My A = A; example was to highlight that aspect in a simple manner.

 > And it's only
 > symmetric syntactically; the associated semantics are profoundly 
asymmetric.

As I said, the types are the same, the number of indirections are the 
same. And internally, I've given examples of IL and native code where 
the operands show the same properties.