Ian Lance Taylor schrieb am Mittwoch, 19. August 2020 um 00:39:16 UTC+2:
> Yes, but here you are assigning the value struct{}{} to the type S.
> That's not how type arguments work: type arguments are not assigned to
> type parameters. Instead, the body of a generic function or type is
> instantiated with the type argument. In a generic function, rather
> than assigning a value struct{}{} to type S, we are replacing
> instances of S in F with struct{}. But struct{} has no methods. So
> can you call method M on an argument whose type is the type parameter?
> Why or why not?
>
Thanks for the explanation.
Given this setup:
type S struct{}
func (s S) M() {}
func F1[T S](s T) { s.M() }
func F2[T struct{}](s T) {}
The instantiations would have to be:
F1[S] :: func(S)
F1[struct{}] :: func(S)
F2[struct{}] :: func(struct{})
F2[S] :: func(struct{})
Non-interface/non-"anyof" constraints would always be instantiated as
themselves.
I can see that this might be surprising. Given that it doesn't add any
value over normal function parameters it is probably not worth it.
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