How does `interface{ AsElement() *Element }` not do exactly what you want?
On Thu, Apr 4, 2024 at 4:14 AM atd...@gmail.com <atd...@gmail.com> wrote:
> Might have come across this today as I was trying to simplify some code.
>
> Basically, I have a base type called *Element that has a method
> AsElement() *Element that returns itself.
>
> And this base element is used as a base for many others, for isntance:
>
> type Div struct{ *Element}
> type Span struct{*Element}
> type Anchor {*Element}
> ...
>
> Somehow, I need a function Ref that can take a pointer to any of these
> elements and modify them (basically modifying the inner *Element pointer).
>
> Currently, I don't think I can abstract over these types which share in
> common the *Element field and the AsEleemnt method promoted from it.
> I don't want to have to implement a specific method to do that mutation
> operation for each and every one of these types either.
>
> Basically, trying to make generic this function:
>
> func Ref(vref **Element) func(*Element) *Element{
> return func(e *Element)*Element{
> *vref = e
> return e
> }
> }
>
>
> Or does anyone see something that I missed?
>
> On Thursday, April 4, 2024 at 2:52:16 AM UTC+2 Adam Manwaring wrote:
>
>> While this would make some things much easier for me, it seems this would
>> be a pretty fundamental change. Constraints are essentially interfaces and
>> interfaces in Go are defined by behaviors. Structs, on the other hand, are
>> defined by properties. There is no behavior that all structs have that
>> every other type couldn't also have. Thus having a struct constraint would
>> be a one-off exception which for the most part seems anathema to Go. In a
>> similar vein, there are many times I'd like an interface to require certain
>> exported properties in addition to behaviors, but this isn't going to
>> happen.
>>
>> On Wednesday, March 27, 2024 at 6:28:19 PM UTC-6 Makis Maropoulos wrote:
>>
>>> Same here @Abraham,
>>>
>>> ResponseType interface {
>>> ~struct{}
>>> }
>>>
>>> Obviously this doesn't work, I would love to see it working though.
>>> On Wednesday 14 September 2022 at 17:48:19 UTC+3 Abraham wrote:
>>>
>>>> I am glad I found this thread because I was just now breaking my head
>>>> figuring out why my <struct constraint> was not working....
>>>>
>>>> On Wednesday, May 18, 2022 at 10:41:29 PM UTC-4 Ian Lance Taylor wrote:
>>>>
>>>>> On Wed, May 18, 2022 at 7:36 PM Jeremy Kassis <jka...@gmail.com>
>>>>> wrote:
>>>>> >
>>>>> > Where exactly did this land? Seems like an important conversation...
>>>>>
>>>>> To date there is no way to write a constraint that requires that a
>>>>> type argument be a struct type.
>>>>>
>>>>>
>>>>> > ```
>>>>> > // RPCHandler passes RPCReq and RPCRes as fn args
>>>>> > func RPCHandler[T RPCReq, S RPCRes](fn func(T, S)) http.HandlerFunc
>>>>> {
>>>>> > return func(w http.ResponseWriter, r *http.Request) {
>>>>> > req := T{}
>>>>> > if err := reqBodyReadAll(w, r, &req); err != nil {
>>>>> > resWriteErr(w, err)
>>>>> > return
>>>>> > }
>>>>> > res := S{}
>>>>> > fn(req, res)
>>>>> > resWriteAll(w, r, res)
>>>>> > }
>>>>> > }
>>>>> > ```
>>>>>
>>>>> I would write simply "var req T" and "var res S".
>>>>>
>>>>> Ian
>>>>>
>>>> --
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