strong enums: why implicit conversion to basetype?

[Simen Kjærås]

On Thu, 26 Jan 2012 23:49:40 +0100, Alvaro <alvaroDotSegura at gmail.com>
wrote:

> El 26/01/2012 14:59, Trass3r escribió:
>> I thought it'd be good to outsource this question from the other thread
>> about enums as flags.
>>
>> Is there any merit in having implicit conversion to the basetype?
>> Imo it only introduces a severe bug source and brings no advantages.
>
>> A better example is something like
>> if (b && Bla.S2) // written '&&' instead of '&' by mistake, will
>> silently pass
>> Heck even +,-,... work.
>
> I kind of agree. I understand enums as a way to define "tags" or flags  
> used to define things like file open mode Read, Write, ReadWrite,  
> endianness BigEndian, LittleEndian, socket type Stream/Packet, etc.  
> things that under the hood are represented by integer numbers but that  
> don't represent *quantities*, so should not work the same way as  
> integers. What is the result of subtracting or multiplying LittleEndian  
> and BigEndian? Does not make sense. Bitwise operations would be OK  
> because logica tags can be combined, but little more.

Sometimes, bitwise operations make sense, other times not. Enums play two
roles in D - that of an enumeration and that of a set of flags. Only for
the latter do bitwise operations make sense.