In fact the diff pkg mentioned above does work but is of no use to me since
for each change it gives back only the field(s) used, not the original
structs (or pointers to them), so I can't see any way back to the original
structs (or their slice indexes).
On Friday, July 14, 2023 at 8:58:41 AM UTC+1 Mark wrote:
> What I really want to do is to be able to diff slices of structs on the
> basis of one single field.
> For example, given:
> ```
> type Item struct {
> I int
> S string
> }
> ```
> and given `a` and `b` are both of type`[]Item`, I want to diff these
> slices based purely on the `S` field, ignoring the `I` field.
>
> This diff pkg <https://pkg.go.dev/github.com/r3labs/diff/v3> claims to be
> able to do this (something I'm testing, so I don't know either way yet),
> but in any case, it is incredibly slow.
>
> On Friday, July 14, 2023 at 8:31:39 AM UTC+1 Peter Galbavy wrote:
>
>> As a slight digression - I thought I was going mad, but 'slices' and
>> 'maps' are new :-) Only in 1.21 though...
>>
>> Well, there is a lot of boiler plate that maps.Keys() will get rid of.
>>
>> On Thursday, 13 July 2023 at 10:06:01 UTC+1 Brian Candler wrote:
>>
>>> Structs are already comparable, but all fields must be the same:
>>> https://go.dev/play/p/XwhSz4DEDwL
>>>
>>> I think your solution with function 'eq' is fine. You can see the same
>>> thing in the standard library in slices.CompactFunc and slices.EqualFunc
>>> https://pkg.go.dev/slices#CompactFunc
>>> https://pkg.go.dev/slices#EqualFunc
>>>
>>> For the case of "ordered" rather than "comparable", have a look at
>>> slices.BinarySearchFunc and related functions.
>>>
>>> On Thursday, 13 July 2023 at 09:29:38 UTC+1 Mark wrote:
>>>
>>>> I have a package which has a function `Do[T comparable](a, b []T)
>>>> Result`.
>>>> I have a struct:
>>>> ```go
>>>> type N struct {
>>>> x int
>>>> y int
>>>> t string
>>>> }
>>>> ```
>>>> Is it possible to make `N` comparable; in particular by a field of my
>>>> choice, e.g., `t`?
>>>>
>>>> Or will I have to make, say, `DoFunc(a, b []N, eq func(i, j N) bool)
>>>> Result` with, say,
>>>> `func eq(i, j N) { return i.t == j.t }`?
>>>>
>>>
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