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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