A possible solution for the opIndexXxxAssign morass

[Denis Koroskin]

On Wed, 14 Oct 2009 18:39:27 +0400, Robert Jacques <sandford at jhu.edu>  
wrote:

> On Wed, 14 Oct 2009 10:31:06 -0400, Andrei Alexandrescu  
> <SeeWebsiteForEmail at erdani.org> wrote:
>
>> Don wrote:
>>> Well timed. I just wrote this operator overloading proposal, part 1.
>>> http://www.prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP7
>>> I concentrated on getting the use cases established.
>>
>> I'm not sure multiplication is generally commutative (e.g. in linear  
>> algebra it isn't). So why should a * x be interchangeable with x * a?
>>
>> Also, the much-discussed identity:
>>
>> x @= y	<-->	x = x @ y
>>
>> is difficult to enforce statically in practice. I think some types  
>> would want to define both to achieve good efficiency. It would be hard  
>> for the compiler to render one unnecessary or to prove that the two are  
>> equivalent.
>>
>>
>> Andrei
>
> When a is a scaler, a * x <=> x * a generally holds. It's only when  
> something isn't a scaler, i.e. x1 * x2 != x2 * x1, that community(?)  
> doesn't hold.

It's commutativity (http://en.wikipedia.org/wiki/Commutativity)