[Development] Naming convention for (scoped) enums

[Tor Arne Vestbø]

I’ve lost track of what you are arguing for here 😊

To bring the discussion back, here are my main points:

1. Scoped enums (enum class) for the sake of avoiding name clashes is useful for global enums, but when the enum lives inside a class, the chance that we’ll see a naming clash is minor, and using scoped enums in that case arguably has negative effects on code writability/readability. As a result, we should update the policy to not mandate scoped enums when the enum lives inside a class.

2. Scoped enums for the sake of type safety is a valid use case, but can be solved by promoting a warning to an error, and as such shouldn’t block us moving forward with #1.

Cheers,
Tor Arne 

> On 14 Aug 2018, at 15:00, Eike Ziller <Eike.Ziller at qt.io> wrote:
> 
> 
> 
>> On 14. Aug 2018, at 13:18, Tor Arne Vestbø <Tor.arne.Vestbo at qt.io> wrote:
>> 
>> 
>>> On 14 Aug 2018, at 13:13, Eike Ziller <Eike.Ziller at qt.io> wrote:
>>> 
>>> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf states the problems that were the driver for creating strongly typed enums:
>>> 
>>> 1. Implicit conversion to integer
>>> 2. Inability to specify underlying type
>> 
>> https://en.cppreference.com/w/cpp/language/enum describes types for unscoped enums too, curious, what’s the difference for the scoped enums?
>> 
>>> 3. Scoping
>>> 
>>>> that specifically mentions the enum inside a class use case a primary driver?
>>> 
>>> Why would the implicit conversion problem be any different for enums inside a class?
>> 
>> It wouldn’t. I was referring to the scoping/name clash, which is what this discussion has been largely focusing on (so far).
> 
> Now you cut off context. I was answering to:
> 
>>>>> 
>>>>> There is one more very important aspect. Scoped enums can have dedicated
>>>> types and are type safe. This could have easily caught issues like (which
>>>> coincidently was pointed out to me this morning):
>>>>> 
>>>>> https://codereview.qt-project.org/#/c/236736/
>>>>> 
>>>>> And I believe that is a very good reason to still prefer scoped enums.
>>>> 
>>>> How frequent is this class of bugs?
>>> 
>>> Frequent enough for it being the primary driver behind the introduction of scoped enums?!?
>> 
>> Do you have a source for this, that specifically mentions the enum inside a class use case a primary driver?
> 
> Which is about type-safety, not scoping.
> 
> -- 
> Eike Ziller
> Principal Software Engineer
> 
> The Qt Company GmbH
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