On Wednesday, 29 December 2021 at 02:33:08 UTC, frame wrote:
On Wednesday, 29 December 2021 at 01:11:13 UTC, Stanislav
Blinov wrote:
Because opIndexAssign cannot distinguish at compile time
between initialization and assignment:
```d
Stuff[Key] aa;
aa[key] = Stuff(args); // ostensibly, initialization
aa[key] = otherStuff; // assignment to existing value
```
Same syntax, different behavior. This can only be caught at
runtime. `require` and `update` though should be able to pull
this off, and that they don't is a bug.
Of course but opIndexAssign() isn't there in my example. The
compiler should call runtime's _aaGetY() or something like that
directly.
It is doing that. You've asked why that should be compile error,
and the answer is - because there's no way to distinguish between
initialization and assignment here. I.e. you can't make one line
compile and the other - not. Either both compile, or both don't.
So if you allow them to compile, you'll have to have a runtime
check, throwing an exception on attempt to assign. Which is just
horrible. Better to leave the assignment a compile error, and
make `require` and `update` do the job they're supposed to be
doing.
