Operator overloading -- lets collect some use cases

[aarti_pl]

Andrei Alexandrescu pisze:
> aarti_pl wrote:
>> Don pisze:
>>> There's been some interesting discussion about operator overloading 
>>> over the past six months, but to take the next step, I think we need 
>>> to ground it in reality. What are the use cases?
>>>
>>> I think that D's existing opCmp() takes care of the plethora of 
>>> trivial cases where <, >= etc are overloaded. It's the cases where 
>>> the arithmetic and logical operations are overloaded that are 
>>> particularly interesting to me.
>>>
>>> The following mathematical cases immediately spring to mind:
>>> * complex numbers
>>> * quaternions (interesting since * is anti-commutative, a*b = -b*a)
>>> * vectors
>>> * matrices
>>> * tensors
>>> * bigint operations (including bigint, bigfloat,...)
>>> I think that all of those are easily defensible.
>>>
>>> But I know of very few reasonable non-mathematical uses.
>>> In C++, I've seen them used for iostreams, regexps, and some stuff 
>>> that is quite frankly bizarre.
>>>
>>> So, please post any use cases which you consider convincing.
>>>
>>
>> DSL support in mother language. As an example I can give SQL in D or 
>> mockup tests description language (usually also in D - not as a 
>> separate script language).
>>
>> In my previous posts I already put few arguments why it is sometimes 
>> much more handy to use "DSL in mother language" approach rather than 
>> string mixins with DSL language itself.
> 
> I saw that, but few, if any, of the arguments you made apply to 
> operators vs. named methods. You argued on string mixins vs. using named 
> symbols. In fact one argument of yours works against you as there's no 
> completion for operators.
> 
> Andrei

I put my argument much earlier in this discussion:
eg. here: 
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=81040

To sum up: using methods to emulate operators is just completely 
unreadable and looks awful. It's very easy to make an error using such a 
technique.

Later, I just replayed to posts convincing that solution for supporting 
DSL languages in D is using string mixins. I believe I could provide a 
few weighty arguments to support my opinion that it is not always best 
solution for this problem. In many cases it is much better to integrate 
DSL into D as a kind of API, not separate sub-language. Then we can get 
some support from IDE, while using string mixins we probably would get 
nothing...

Best Regards
Marcin Kuszczak
(aarti_pl)