Well, the first allows one Less per package, the second allows one per
type. Since I tend to have multiple types in a package I find that more
readable.
Anyway, I finally fixed the problem with mixture of reflect and type
assertion
val := reflect.ValueOf(b)
if val.Kind() == reflect.Slice {
leng = val.Len() // outer length
for i := 0; i < leng; i++ {
v := val.Index(i)
if v.Kind() == reflect.Slice {
sz = v.Len() // inner length
for j := 0; j < sz; j++ {
vv := v.Index(j)
if m, ok := vv.Interface().(Useable); ok {
n, ok :=
reflect.ValueOf(a).Index(i).Index(j).Interface().(Useable)
if !ok {
log.Fatal("a is not the same type as b")
}
good = m.Equal(n)
} else {
log.Fatal("Candidate cannot be converted to a Usable type")
}
}
}
}
}
Yeah it's a bit ugly and I'm working on something better, but the immediate
issue is closed for now, so thanks everyone for the kick in the right
direction.
Regards
Chris
On Thursday, 1 February 2018 18:55:27 UTC, Axel Wagner wrote:
>
> I don't really see the difference in writing
> func Less(a, b *T) bool
> and
> func (a *T) Less(b *T) bool
> convenience wise - except that the latter requires the name to be exported
> and doesn't allow using a function literal (so, yeah, the latter actually
> seems significantly *less* convenient).
>
> On Thu, Feb 1, 2018 at 7:51 PM, Chris Hopkins <cbeho...@gmail.com
> <javascript:>> wrote:
>
>> No, was hoping to use the interface (It's the only reason I defined it)
>> to test if two items are equal.
>> I guess I could enforce that you have to supply the equals function like
>> the sort interface does. I was just hoping for more.
>>
>> I'll have a rethink next time I have time.
>>
>> Thanks
>>
>> On Thursday, 1 February 2018 18:46:09 UTC, Axel Wagner wrote:
>>>
>>> On Thu, Feb 1, 2018 at 11:52 AM, Chris Hopkins <cbeho...@gmail.com>
>>> wrote:
>>>
>>>> Yeah, so having played with this. It seems that this is going to take
>>>> some judicious use of reflect if I'm to stand any chance of maintaining a
>>>> flexible API, which I really hoped to avoid.
>>>>
>>>
>>> I'm 99% sure that you don't have to use reflect at all. You only have to
>>> swap elements around, that's kind of what sort.Interface was made for. It
>>> already comes with implementations for slices of common datatypes and you
>>> can make a function that works on arbitrary slices with less than ten lines
>>> of reflect code.
>>>
>>> Like, I *really* don't understand your problem.
>>>
>>>
>>>> I had assumed that the point of interfaces was to avoid this. I guess
>>>> from a high level I don't see why a slice of type is really that different
>>>> from a type. But I have never written a compiler so I'm sure that it's way
>>>> more complex than it seems. :-)
>>>>
>>>> Thanks for the help.
>>>> Chris
>>>>
>>>>
>>>> On Thursday, 1 February 2018 00:42:04 UTC, simon place wrote:
>>>>>
>>>>> also notice, if you haven’t encountered it, this makes []interfaces a
>>>>> bit awkward to handle with ellipsis functions...
>>>>>
>>>>> https://play.golang.org/p/JWuc4jt2uSP
>>>>>
>>>>> what i do is this;
>>>>>
>>>>> https://play.golang.org/p/O9Q4K_vXlul
>>>>>
>>>>> but you will need a convert for all combinations of interfaces and
>>>>> ellipsis functions you have!
>>>>>
>>>>> from what i understand ellipsis functions are implemented simply as
>>>>> auto-magic slices, rather than expanded out, so the function doesn’t
>>>>> apply
>>>>> the interface wrapping like with individual parameters.
>>>>>
>>>>> --
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>>>>
>>>
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>
>
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