On Thu, Jan 7, 2021 at 9:33 AM Axel Wagner
<axel.wagner...@googlemail.com> wrote:
>
> On Wed, Jan 6, 2021 at 11:31 PM Amit Saha <amitsaha...@gmail.com> wrote:
>>
>> In the description of context.WithValue(), we have:
>>
>> The provided key must be comparable and should not be of type string
>> or any other built-in type to avoid collisions between packages using
>> context. Users of WithValue should define their own types for keys. To
>> avoid allocating when assigning to an interface{}, context keys often
>> have concrete type struct{}.
>>
>> I am wondering if someone can explain what exactly comparable means here?
>>
>> In other languages and Go
>> (https://golang.org/ref/spec#Comparison_operators), comparable usually
>> means being able to compare two values for equality/greater/lesser.
>
>
> The linked spec section actually contradicts that:
>
>> The equality operators == and != apply to operands that are comparable. The
>> ordering operators <, <=, >, and >= apply to operands that are ordered.
>
>
> (emphasis from the spec). So, the definition of "comparable" is "can be used
> with == and !=" and what exactly that means is listed below that quote.
>
> Hope that helps
>
Thanks for pointing it out. I missed that - we have two things here,
ordered and comparison here then.
Is it fair to say then that any user-defined type here is acceptable as a key?
>>
>> Thanks,
>> Amit.
>>
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