If you have type checking / casting / type select, whatever you want to call it
in the “generic code”, it is not generic, and not re-usable.
You can’t possibly know all the possible types, there may even be more
additional primitive types, so the code is not resilient - Go 2.1 and all of
your library code breaks?
The caller will not have access to the source code (and certainly not want to
read it to call a function). Nothing will be obvious as to what Sum can work on
or what it does - in fact you can have very subtle errors because the code is
duplicated across types.
Besides those problems, even if it was somehow workable, the syntax reuses
keywords in non-standard ways (for example even if this was adopted, why
wouldn’t the syntax be:
switch K {
case (int64,unint64,…):
blah blah blah
case big.Int
blah blah blah
default:
panic // implied
}
The compiler already knows K is a type…
And yet more problems, because you probably need every combination of types if
it has more than one, (depending on what the method does) — you need an n*n
number' of case statements to implement it….
I am just being realistic, and I don’t mean to be harsh, but I don’t think your
proposal is going to be accepted, and I think it might be better if you spent
more time listening to the criticism, and maybe reworking, than trying to
defend it. I guess there is always the chance I don’t get it, but I think I do…
Not sure how else to explain it.
> On Sep 18, 2018, at 3:53 PM, Wojciech S. Czarnecki <o...@fairbe.org> wrote:
>
> On Tue, 18 Sep 2018 10:11:52 -0700 (PDT)
> mhhc...@gmail.com wrote:
>
>> I agree with Robert, this is not re usable.
>
> What is not reusable? A generic Sum function allowed by
> the CGG that can sum any type of any base that accidentally
> has anything countable in it?
>
>> I much prefer this
>>
>> func Sum(some []K, add func(l,r K) K) (ret K) {
>> for _, v := range some {
>> ret = add(ret, v)
>> }
>> return ret
>> }
>>
>> func main(){
>
>
>> total := Sum([]int{1,2,3,4}, func(l,r int) int {return l+r})
>> }
>
> How clever and generic it looks. Generic, javish and cpluplusish.
> And how readable call site it gave.
>
> In CGG Go user code call is exactly the same for ANY type.
>
> total := Sum(x) // For var x []AnyType. ANY.
>
> var x []string
> total := Sum(x)
>
> may return sum of all runes in all strings and sprintf-ed to
> the resulting string.
>
>> this is not re usable.
>
> How can I call your example to get string result of sum of all
> runes? CGG's is as with any other type: `total := Sum(x)`
>
> --
> Wojciech S. Czarnecki
> << ^oo^ >> OHIR-RIPE
>
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