Debug help - opDispatch - unknown member function

[Brother Bill]

On Tuesday, 9 September 2025 at 00:45:00 UTC, monkyyy wrote:
> On Tuesday, 9 September 2025 at 00:40:31 UTC, Brother Bill 
> wrote:
>> https://tour.dlang.org/tour/en/gems/opdispatch-opapply
>>
>> This states: "Any unknown member function call to that type is 
>> passed to opDispatch, passing the unknown member function's 
>> name as a string template parameter."
>>
>> [...]
>
> you didnt define "callhome" so the the mixin fails, this 
> propagates a "__error" or something, and opDispatch when it 
> contains an error doesnt pass it up the stack

Then I'm not clear what an "unknown" member function name means.

Kindly provide an example.