How do I check if this field is of this template struct?

[Steven Schveighoffer]

On 3/19/21 12:41 PM, Jack wrote:
> On Friday, 19 March 2021 at 08:54:50 UTC, Paul Backus wrote:
>> On Friday, 19 March 2021 at 07:14:46 UTC, Jack wrote:
>>> give below template struct, how can I list the members x, y and z? 
>>> I've tried something with OriginalType and TemplateOf but no luck... 
>>> it seems if I do foo!"str1" the "str1" became "part of type"? give 
>>> .stringof from typeof(__traits(getMember, foo, field)) I thought the 
>>> type would be foo!string or something.
>>
>> You want std.traits.isInstanceOf:
>>
>>     static if(!isType!m && isInstanceOf!(foo, typeof(m)))
> 
> thanks this works fine outside a method but not in a static method. what 
> am I missing?
> 
> void main()
> {
>          // doesn't print anything
>      Foo.list();
> }
> 
> alias Foo = foo!();
> 
> template foo(string s = null)
> {
>      @nogc
>      struct foo
>      {
>          int n;
> 
>          enum x = foo!"str1"(10);
>          enum y = foo!"str2"(20);
>          enum z = foo!"str3"(30);
> 
>          enum myEnum { none }
> 
>          void someMethod() { }
> 
>          static void list()
>          {
>              //writeln("members = ", [__traits(allMembers, foo!())]);
>              static foreach(field; __traits(allMembers, foo!()))
>              {{
>                  alias m = __traits(getMember, foo!(), field);
>                  static if(!isType!m && isInstanceOf!(foo, typeof(m)))

foo in this context is the *instantiated* foo (i.e. the struct foo 
above). What you want is `isIsntanceOf!(.foo, typeof(m))`

-Steve