You should use interfaces and a “node” type.
> On Dec 20, 2021, at 12:07 PM, Michael Ellis <michael.f.el...@gmail.com> wrote:
>
> >Just to be clear, the way I understood you is that you want HtmlTree.C to
> be a slice which has elements which can each either be a string or an
> *HtmlTree - i.e. you want these to be mixed in a single slice. Correct?
>
> Actually, no. An HtmlTree instance whose content is a string is a terminal
> node. The recursion in the Render() func looks like:
>
> for _, c := range h.C {
> switch c := c.(type) {
> case string:
> b.WriteString(c)
> case *HtmlTree:
> err = Render(c, b, rindent)
> if err != nil {
> return fmt.Errorf("%s : %v", h.T, err)
> }
> default:
> return fmt.Errorf("Bad content %v. Can't render type
> %T! ", h.C, c)
> }
> }
>
> I suppose it's still a problem, though, since the compiler doesn't have any
> way of knowing that's how trees of HtmlTree meant to be constructed. I should
> have expressed the intended constraint on HtmlTree.C as `string |
> []*HtmlTree`. Does that make a difference?
>> On Monday, December 20, 2021 at 10:25:26 AM UTC-5 axel.wa...@googlemail.com
>> wrote:
>> Just to be clear, the way I understood you is that you want HtmlTree.C to be
>> a slice which has elements which can each either be a string or an *HtmlTree
>> - i.e. you wan these to be mixed in a single slice. Correct?
>> Because that is not a use case for generics, it's a use case for sum types
>> (which Go does not have).
>>
>>> On Mon, Dec 20, 2021 at 4:11 PM Michael Ellis <michael...@gmail.com> wrote:
>>> > They can't, sorry.
>>> Ok. Thanks, Axel.
>>> Saves me wasting more time. In the past 3 years of using Go, this is the
>>> only use case where I've really wanted generics (other cases I've
>>> encountered so far are easily handled with code generation).
>>
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>
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