Is there an alternative to "__FUNCTION__" that gives the actual function symbol and not the name as a string?

Simon simon.vanbernem at
Sat Oct 23 19:52:19 UTC 2021

On Saturday, 23 October 2021 at 19:03:41 UTC, Tim wrote:
> On Saturday, 23 October 2021 at 18:56:48 UTC, Simon wrote:
>> And I tried to use your suggestion like this:
>> enum OUTPUT_REPRO_CASE(alias func = __traits(parent, {})) = 
>> "build the actual code stuff with"~fullyQualifiedName!func~" 
>> and so on";
>> Which doesn't work. In that case func seems to become the 
>> parent namespace. If I substitute fullyQualifiedName!func with 
>> fullyQualifiedName!(__traits(parent, {}))) I get a circular 
>> dependecy error.
>> How do I have to use this exactly?
> This seems to work:
> import std.traits, std.stdio;
>     string name = fullyQualifiedName!(__traits(parent, {}));
>     writeln(name);
> };
> void test()
> {
>     mixin(OUTPUT_REPRO_CASE);
> }
> void main()
> {
>     test();
> }

Thanks for putting up with me! I tried a bunch and it seems like 
I left out too much code, because I can't get it working 100%. I 
didn't even know about the q{} syntax, so I didn't think the 
stuff I left out would matter, but when using this approach it 
apparently does. I am going to show the full code here, just so 
that there are no more suprises.

Sorry for this becoming a "please do my homework" kind of 
question. I tried for half an hour with no idea how to fix the 
errors I'm seeing. Something always fails.

The full implementation of OUTPUT_REPRO_CASE looked like this:

enum MAKE_FUNCTION_REPRODUCIBLE(alias func, s64 
execution_count_to_log_reproduction_on = -1) =
   "static s64 execution_count = 0;
     dlog(\""~fullyQualifiedName!func~" call count: %lld\", 

   if(execution_count == 


It calls the function

String generate_reproduction_for_current_function_call(alias 
func, string[] parameter_names, Parameter_Types...)(Allocator* 
allocator, Parameter_Types parameters);

that actually creates the code-string. I did a lot of trial and 
error getting the trait-calls to expand at the right time (become 
part of the mixin string or outside of it) and falling on my nose 
about when something is a type vs a string and so on, so this 
became really ugly. If you have a better suggestion I'm open to 

I was testing this inside the function

Dynamic_Array!(Polygon) clip_polygons(Slice!Vector2 p0, 
Slice!Vector2 p1, bool return_difference_instead_of_union = true, 
Slice!(Slice!Vector2) p0_holes = Slice!(Slice!Vector2)(), bool 
debug_print = false);

in which the OUTPUT_REPRO_CASE expands to:

static s64 execution_count = 0;
     dlog("vbl.clip_polygons call count: %lld", execution_count);

   if(execution_count == -1L){
       ["p0", "p1", "return_difference_instead_of_union", 
"p0_holes", "debug_print"])(
       p0, p1, return_difference_instead_of_union, p0_holes, 


When I try to change the whole thing to be a token string, 
execution_count_to_log_reproduction_on was suddenly undefined. I 
changed this to be an abominational mix of token string and 
string literal and then it sort of worked, except then the whole 
business of making the parameter names expand as actual tokens 
and not strings failed for some reason.

I am super confused (this is a reccuring theme with D compile 
time stuff on my part :/). Can you show me how this can work with 
your token string solution?

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