>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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