On Wed, Aug 31, 2022 at 7:28 AM antonio.o...@gmail.com <
antonio.ojea.gar...@gmail.com> wrote:
> Hi,
>
> Based on the documentation:
>
> "The map key can be any type that is comparable."
> "Struct values are comparable if all their fields are comparable. Two
> struct values are equal if their corresponding non-blank fields are equal."
> "Interface values are comparable. Two interface values are equal if they
> have identical dynamic types and equal dynamic values or if both have value
> nil."
>
> My understanding is that I can use an structure like this as a key for a
> map
>
> type dialer interface {
> dial()
> }
>
> type key struct {
> id string
> number int
> dialer dialer
> }
>
> It also seems to work fine https://go.dev/play/p/hKQfx-JH5WP
>
This works in general, but your example is flawed. In your example, you have
f1 := &fakedialer{}
f2 := &fakedialer2{}
and then use f1 anf f2 as keys. These are pointers to structs, so the
comparison will be pointer comparison, not field-by-field comparison.
If you do:
f1 := fakedialer{}
f2 := fakedialer2{}
and replace the pointer receivers with value receivers, and then use these
as map keys, it will work. But this time, if you pass a struct that cannot
be used as a key, you'll receive a runtime panic instead of a compile error.
> But I'm wondering if I'm missing something or are there some corner cases
> I should take into account before doing this ... or if this is not
> recommended at all
>
> Thanks,
>
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