Pop quiz, what does this do?

[Steven Schveighoffer]

On 3/3/21 11:42 AM, Max Haughton wrote:
> On Wednesday, 3 March 2021 at 16:06:48 UTC, Steven Schveighoffer wrote:
>> The FieldNameTuple from std.traits returns a tuple of names of all the 
>> fields that are present on a type instance.
>>
>> What about the result on things that can't have fields?
>>
>> import std.traits;
>>
>> interface I
>> {
>>    int foo();
>> }
>>
>> pragma(msg, FieldNameTuple!I);
>>
>> Without looking up the docs, or trying it, what do you think it does?
>>
>> -Steve
> 
> "" - difference between a field and a member I'm guessing


No, it's not. A member that's not a field doesn't normally produce 
anything in the tuple.

Try this one:

interface I
{
    int foo();
    int bar();
}

-Steve