either

[Nick Sabalausky]

"Nick Sabalausky" <a at a.a> wrote in message 
news:igd57p$2k1k$1 at digitalmars.com...
> "Andrei Alexandrescu" <SeeWebsiteForEmail at erdani.org> wrote in message 
> news:igcvll$29k5$1 at digitalmars.com...
>>I wrote a simple helper, in spirit with some recent discussions:
>>
>> // either
>> struct Either(Ts...)
>> {
>>     Tuple!Ts data_;
>>     bool opEquals(E)(E e)
>>     {
>>         foreach (i, T; Ts)
>>         {
>>             if (data_[i] == e) return true;
>>         }
>>         return false;
>>     }
>> }
>>
>> auto either(Ts...)(Ts args)
>> {
>>     return Either!Ts(tuple(args));
>> }
>>
>> unittest
>> {
>>     assert(1 == either(1, 2, 3));
>>     assert(4 != either(1, 2, 3));
>>     assert("abac" != either("aasd", "s"));
>>     assert("abac" == either("aasd", "abac", "s"));
>> }
>>
>> Turns out this is very useful in a variety of algorithms. I just don't 
>> know where in std this helper belongs! Any ideas?
>>
>
> For years I've just been doing this:
>
> if( [1, 2, 3].contains(1) )
>
> Although I think I needed to write a new "contains" to wrap existing 
> functions when I switched from Tango to Phobos.
>
> Of course, "1 in [1,2,3]" would be much better ;) But whateever. Either 
> way.
>
> But I suppose your "either" avoids an allocation, doesn't it? (And I'd 
> lean more towards "any" than "either" like the other people).
>

It'd be really cool to have that work for the other comparison operators, 
too.