Attributes on Enum Members: Call for use cases.

[Seb]

On Tuesday, 28 November 2017 at 19:38:44 UTC, Meta wrote:
> On Tuesday, 28 November 2017 at 02:20:15 UTC, Michael V. 
> Franklin wrote:
>> On Sunday, 19 November 2017 at 13:35:13 UTC, Michael V. 
>> Franklin wrote:
>>
>>> What's the official word?  Does it require a DIP?
>>
>> For those who might want to know, Walter has informed me that 
>> this change will require a DIP.  I already  have two DIPs in 
>> the queue right now, so I wouldn't mind if someone else wrote 
>> it.
>>
>> But, absent any volunteers, I would welcome all of you to 
>> reply to this thread with some use cases where you might find 
>> UDAs or other attributes useful on enum members.  Deprecation 
>> and serialization have already been mentioned, but it'd be 
>> impossible for me to imagine all the different ways users 
>> might find this feature useful.
>>
>> Thanks,
>> Mike
>
> I'd be interested in working on a DIP like this Michael, but I 
> also want to expand the scope to allowing UDAs on function 
> arguments as well. We should have some solid use cases in mind; 
> let's take this to private email.

UDAs for function arguments would be really awesome to have. Just 
imagine how nice the Vibe.d web routes would look like:

auto postUser(@body User user, @errors Errors errors)

Instead of:
@body("user")
@errorDisplay
auto postUsers(User _user, string  _error)



Or:

@path("/users/:id")
auto getUser(@urlParam string id, @queryParam int page, @auth 
User user)

Instead of:

@path("/users/:id")
@queryParam("page")
@before!authenticate("user")
auto getUsers(string _id, int page, User user)


(This is pseudo-syntax as I write this from my phone).