Wrong enum comparisons

[Dmitry Olshansky]

On 28.05.2012 12:58, Denis Shelomovskij wrote:
> 27.05.2012 23:45, bearophile написал:
>> In some code I have created a small bug that can be reduced to something
>> like this, that the D compiler has not caught at compile-time:
>>
>>
>> enum E1 { A, B }
>> enum E2 { C, D }
>> void main() {
>> E1[2] a;
>> with (E2)
>> assert(a[0] == D);
>> }
>>
>>
>> Why isn't D able to statically tell when you compare values of different
>> enums?
>> How much work is implementing this compile-time test inside the D
>> front-end?
>>
>> Thank you,
>> bye,
>> bearophile
>
> Enumerations are in very poor state in D now. May be, it should be
> deprecated just like typedef and be library-implemented. Why? Because we
> do need really strict type/operation checking with enum so one have to
> write explicitly casts to do non-standard things. The two main
> enumeration types are:
> * list - must hold only one value, only opAssign and opEqual are
> allowed, by default nextValue = prevValue + 1 starting with 0
> * flags - must hold superposition of values, like list, but binary
> operations are also allowed, by default nextValue = prevValue << 1
> starting with 1
>

+1. Well said, hard to add anything ;)

> These also allow finally implement right to!string for flags.
>
> By the way, current enums can be modified to correspond "list"
> enumeration and flags can be added as library component.
>


-- 
Dmitry Olshansky