On Thu, Jun 17, 2021 at 9:43 AM Joshua <joshua.oconno...@gmail.com> wrote:
> Hello,
>
> I have 2 questions about idiomatic ways to represent optional values,
> and variant values in types.
>
> 1) I'm modelling a data type which has a field which may or may not be
> there, would most Gophers reach for a pointer here, and use `nil' to
> represent a missing value?
>
I don't know about "most Gophers" (it's hard to generalize), but I would.
>
> 2) Another field of this type contains an "Action", the variants of
> which hold different information. In nonsense code, I want this:
>
> ,----
> | type EmailAction struct {
> | Summary string
> | Decsription string
> | To string
> | Attendee person
> | }
> |
> | type DisplayAction struct {
> | Description string
> |
> | }
> |
> | type Event struct {
> | OptionalField *MyType
> | Action EmailAction OR DisplayAction
> | }
> `----
>
>
> How would you go about modelling this type in Go?
>
Either using an interface, or by having two pointer-fields and only setting
one.
Depending on the details, it might also be worth considering inverting the
relationship:
type Event struct {
OptionalField *MyType
…
}
type EmailEvent struct {
Event
Summary string
…
}
type DisplayEvent struct {
Event
Description string
…
}
> Or alternatively, do
> you think trying to use "Type Driven Design" like this is not a good fit
> for Go, and rather I should just have a generic set of components and
> validate when functions call it.
>
> Personally I prefer the previous, I really like the idea of knowing a
> type can't exist in an invalid state! Helps me not have to keep track of
> so much in my head.
>
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