How to correctly generate enums at compile time.

[Kevin Balbas via Digitalmars-d-learn]

On Sunday, 30 April 2017 at 20:58:36 UTC, jkpl wrote:
> On Sunday, 30 April 2017 at 20:05:59 UTC, Kevin Balbas wrote:
>> I've got the following code snippet, which almost does what I 
>> want.
>>
>> struct TaggedType {}
>>
>> @TaggedType
>> struct Foo {}
>>
>> @TaggedType
>> struct Bar {}
>>
>> string GenerateTypeEnum()
>> {
>>     string enumString = "enum TypeEnum {";
>>     foreach (name; __traits(allMembers, mixin(__MODULE__)))
>>     {
>>         import std.traits;
>>         static if (hasUDA!(mixin(name), TaggedType))
>>         {
>>             enumString ~= name;
>>             enumString ~= "Type,";
>>         }
>>     }
>>     enumString ~= "}";
>>     return enumString;
>> }
>>
>> // generates enum TypeEnum {FooType,BarType,}
>> mixin(GenerateTypeEnum());
>>
>> This works great, except that TypeEnum isn't accessible from 
>> other modules (undefined identifier 'TypeEnum'), which is kind 
>> of the point of doing this (I'm using the enum as a 
>> system-wide tag for inter-thread communication).  I can 
>> imagine why this would be the case, but it's a pretty serious 
>> problem.  Is there a way to do this?
>
> if i put your sniped in b.d and import in a.d b then i'm able 
> to access TypeEnum.
> You r problem must be something stupid that's not related to 
> UDA/mixins.
>
> That leads to this question (sorry) but at least do you import 
> the module that contains TypeEnum ?

Yes, and in fact, if I manually comment out the code (in my 
actual program, not the test program) in the same module and 
replace it with a hard-coded enum, the other code can access it 
perfectly.  I wouldn't be surprised if it was something stupid, 
but I'm not even sure what could go wrong between those two 
cases.  I figured it was some kind of ordering thing, but I 
honestly have no idea.

Strangely enough, it does work fine in the test snippet, so I'm 
trying to figure out what could be going on since I literally 
copied the function verbatim from my test program to my main one. 
  Now that I've realized this I'm working on how to repro it in 
the smaller program.