No, there isn't, but you can check if the value exists:
x, ok := m[k]
if !ok {
panic("does not exist")
}
You can also wrap that with methods, if you want to avoid the extra check.
I disagree with you that panicking on a non-existent key is better - either
in general, or in the majority of cases. Personally, I don't think I
encountered many use-cases where the zero-value wasn't the perfect thing to
use. I'm not saying your use-case doesn't exist or even that it's rare,
just that I don't think you can generalize from your experience here.
On Thu, Aug 13, 2020 at 8:36 PM Joe Marty <joe.ma...@smartersorting.com>
wrote:
> I'm very new to Go - apologies in advance if I'm missing something:
>
> I find it frustrating that there's no way to create a map that does *not*
> automatically return a zero value for undefined key access by default.
>
> I love the fact that Go doesn't return "nil" for this use case (I love
> Ruby, but I don't think they got that quite right), but returning a default
> value is worse! It would make so much more sense if it would just panic
> when accessing an undefined key. I'm not a Python guy, but I think this is
> something Python got right.
>
> Creating a map that returns some default value when you access an
> undefined key should be a special kind of map, or a special argument to
> initializing the map (which Ruby does allow). In Go, is there even any way
> to create a map that panics when you access an undefined key?
>
> -Joe
>
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