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)
