• Anonymouse (33/33) Feb 15 I want to get a reference to a parent function from inside a
• Inkrementator (22/23) Feb 16 As a workaround, you can define a useless symbol and get the

Anonymouse <zorael gmail.com> writes:

I want to get a reference to a parent function from inside a 
nested function. I need it for `getUDAs!(parentFunction, 
attribute)`.

`__traits(parent, mixin(__FUNCTION__))` works inside the parent 
function and gives me the module, but `mixin(__FUNCTION__)` alone 
inside the nested function immediately errors.

```d
module foo;

void bar(string s, int i)
{
     assert(__FUNCTION__ == "foo.bar");
     alias parentModule = __traits(parent, mixin(__FUNCTION__));
     assert(is(parentModule == module));

     void dg()
     {
         assert(__FUNCTION__ == "foo.bar.dg");
         alias parentFunction = __traits(parent, 
mixin(__FUNCTION__));
     }
}

void main() {}
```

```
onlineapp.d(12): Error: function `bar` is not callable using 
argument types `()`
onlineapp.d(12):        too few arguments, expected 2, got 0
onlineapp.d(3):        `foo.bar(string s, int i)` declared here
```

So `mixin(__FUNCTION__)` seems to be trying to call the parent 
function rather than giving me the symbol of the nested one, like 
`foo.bar().dg`. I tried making it `mixin("&" ~ __FUNCTION__)` but 
it did not help.

How can I make this work?

Inkrementator <invalid invalid.org> writes:

On Sunday, 16 February 2025 at 07:38:09 UTC, Anonymouse wrote:
 How can I make this work?

As a workaround, you can define a useless symbol and get the 
parent of that.
```
module foo;

void bar(string s, int i)
{
     assert(__FUNCTION__ == "foo.bar");
     alias parentModule = __traits(parent, mixin(__FUNCTION__));
     assert(is(parentModule == module));

     void dg()
     {
         assert(__FUNCTION__ == "foo.bar.dg");
	enum n = 0;
         alias parentFunction = __traits(parent, __traits(parent, 
n));
	pragma(msg, __traits(identifier, parentFunction)); // bar
	pragma(msg, __traits(identifier, __traits(parent, n))); // dg

     }
}

void main() {}
```