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From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: What's wrong with C++?
Date: Thu, 17 Feb 2011 19:53:17 +0100
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Date: 2011-02-17T19:53:17+01:00
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Yannick Duchêne writes on comp.lang.ada:
> Le Wed, 16 Feb 2011 21:07:02 +0100, Hyman Rosen
> <hyman.rosen@gmail.com> a écrit:
>> This is legal C++:
>>
>>     struct DamageType {
>>         enum E { Fire = 1, Acid = 2, Lightning = 4, Poison = 8 };
>>     };
>>
>>     DamageType::E what_my_dragon_can_do =
>>         DamageType::E( DamageType::Acid | DamageType::Poison );
>
> I forget C++ for long I am not aware of its updates since this
> time. Does what you wrote mean C++ can restict the possible value of
> an enumeration ?  Can derive subsets ?

No, it only means that enumerations in C++ really are integers and not
enumerations.  Otherwise, how could the value Acid | Poison be in the
set { Fire, Acid, Lightning, Poison } ?

Hyman explained that enum values can be "promoted" automatically to int,
but now he's just shown that ints such as the result of the bitwise OR
of two enum values can also be "promoted" automatically to an enum type.

Blech.

-- 
Ludovic Brenta.