Thank you. Zero values are of course identical. I was only thinking about
the pointer case...
On Sunday, May 28, 2023 at 5:10:33 PM UTC+2 burak serdar wrote:
> Two values A and B are equal (A==B) if A and B have the same type and the
> same values. In a code where
>
> a:=clientContextKey{}
> b:=clientContextKey{}
>
> a==b is true, because they have the same types, and they have the same
> values (i.e. the empty value).
>
> Note however:
>
> a:=&clientContextKey{}
> b:=&clientContextKey{}
>
> It is not guaranteed that a==b, neither is it guaranteed that a!=b. The
> compiler may choose to allocate the same address for the zero-size
> variables a and b, or it may not,
>
> On Sun, May 28, 2023 at 7:01 AM cpu...@gmail.com <cpu...@gmail.com> wrote:
>
>> I've recently stumbled across code like this
>> https://go.dev/play/p/u3UER2ywRlr:
>>
>> type clientContextKey struct{}
>>
>> ctx := context.Background()
>> ctx = context.WithValue(ctx, clientContextKey{}, "foo")
>> _, ok := ctx.Value(clientContextKey{}).(string)
>>
>> Naively, I had expected this to fail since I assumed that
>> clientContextKey{} would create a new variable instance every time it was
>> used and hence the keys would not match.
>>
>> Why does this use of instantiating the struct type work here?
>>
>> Thanks,
>> Andi
>>
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>
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