Thread overview
Can I count the of enum's fields at compile time?
Nov 23, 2017
Marc
Nov 23, 2017
Marc
Nov 23, 2017
Jonathan M Davis
Nov 23, 2017
Marc
Nov 23, 2017
Ali Çehreli
Nov 23, 2017
Marc
November 23, 2017
for example:

enum A { a = -10, b = -11, c = -12, d = -13, e = -34}

enum int countOfA = coutOfFields(A); // 5 fields

November 23, 2017
On Thursday, 23 November 2017 at 00:58:21 UTC, Marc wrote:
> for example:
>
> enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
>
> enum int countOfA = coutOfFields(A); // 5 fields

https://dlang.org/spec/traits.html#allMembers

enum A { a = -10, b = -11, c = -12, d = -13, e = -34}

enum int countOfA = __traits(allMembers, A).length; // 5 fields

static assert(countOfA == 5);

Mike
November 23, 2017
On Thursday, 23 November 2017 at 01:01:42 UTC, Michael V. Franklin wrote:
> On Thursday, 23 November 2017 at 00:58:21 UTC, Marc wrote:
>> for example:
>>
>> enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
>>
>> enum int countOfA = coutOfFields(A); // 5 fields
>
> https://dlang.org/spec/traits.html#allMembers
>
> enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
>
> enum int countOfA = __traits(allMembers, A).length; // 5 fields
>
> static assert(countOfA == 5);
>
> Mike

This was fast! Thanks
November 22, 2017
On Thursday, November 23, 2017 00:58:21 Marc via Digitalmars-d-learn wrote:
> for example:
>
> enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
>
> enum int countOfA = coutOfFields(A); // 5 fields

import std.traits;

enum countOfA = EnumMembers!A.length;

- Jonathna M Davis

November 23, 2017
On Thursday, 23 November 2017 at 01:04:29 UTC, Jonathan M Davis wrote:
> On Thursday, November 23, 2017 00:58:21 Marc via Digitalmars-d-learn wrote:
>> for example:
>>
>> enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
>>
>> enum int countOfA = coutOfFields(A); // 5 fields
>
> import std.traits;
>
> enum countOfA = EnumMembers!A.length;
>
> - Jonathna M Davis

This sounds more readable. I was going to write a "function extension" to enum but I think it isn't really needed. Thank you too.
November 22, 2017
On 11/22/2017 05:21 PM, Marc wrote:
> On Thursday, 23 November 2017 at 01:04:29 UTC, Jonathan M Davis wrote:
>> On Thursday, November 23, 2017 00:58:21 Marc via Digitalmars-d-learn wrote:
>>> for example:
>>>
>>> enum A { a = -10, b = -11, c = -12, d = -13, e = -34}
>>>
>>> enum int countOfA = coutOfFields(A); // 5 fields
>>
>> import std.traits;
>>
>> enum countOfA = EnumMembers!A.length;
>>
>> - Jonathna M Davis
> 
> This sounds more readable. I was going to write a "function extension" to enum but I think it isn't really needed. Thank you too.

As an eponymous template:

enum One { a }
enum Three { a, b, c }

import std.range : EnumMembers;
enum countOf(E) = EnumMembers!E.length;

unittest {
    static assert(countOf!One == 1);
    static assert(countOf!Three == 3);
}

void main() {
}

Ali
November 23, 2017
On Thursday, 23 November 2017 at 01:34:54 UTC, Ali Çehreli wrote:
> On 11/22/2017 05:21 PM, Marc wrote:
>> On Thursday, 23 November 2017 at 01:04:29 UTC, Jonathan M Davis wrote:
>>> On Thursday, November 23, 2017 00:58:21 Marc via Digitalmars-d-learn wrote:
>>>> [...]
>>>
>>> import std.traits;
>>>
>>> enum countOfA = EnumMembers!A.length;
>>>
>>> - Jonathna M Davis
>> 
>> This sounds more readable. I was going to write a "function extension" to enum but I think it isn't really needed. Thank you too.
>
> As an eponymous template:
>
> enum One { a }
> enum Three { a, b, c }
>
> import std.range : EnumMembers;
> enum countOf(E) = EnumMembers!E.length;
>
> unittest {
>     static assert(countOf!One == 1);
>     static assert(countOf!Three == 3);
> }
>
> void main() {
> }
>
> Ali

whoa, this is so easy and elegant. I'm falling in love with D. Thank you too!