Quoting roger peppe (2018-11-25 12:01:08)
> On Sun, 25 Nov 2018 at 16:54, 'Axel Wagner' via golang-nuts
> <[1]golang-nuts@googlegroups.com> wrote:
>
> I'd suggest simply
> func (b *Binlog) writeArgumentToOutput(writer writer, arg uint64) error
> { /* do the writing */ }
> and doing the actual conversions at the call-site. It's type-safe,
> shorter, faster and more idiomatic - with the tiny downside of a
> `uint64()` here and there.
> Alternatively, use reflect as it's intended to - something like
> func� writeArgumentToOutput(writer writer, arg interface{}) error {
> � � rv := reflect.ValueOf(arg)
> � � var v uint64
> � � if k := rv.Kind(); k >= reflect.Int && k < reflect.Uint {
>
> I know constants are protected by the Go compatibility guarantee, doing
> range comparisons on reflect.Kind constants seems a bit dubious to me.
> Without going to the definitions, it's not clear to the reader which
> exact kinds are included here. I'd suggest enumerating all the expected
> kinds directly in a switch statement (the compiler may well optimize to
> a range comparison for that anyway).
I agree; had to stare at this a bit. Something like:
switch rv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
v = uint64(rv.Int())
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32,
reflect.Uint64:
v = rv.Uint()
default:
return fmt.Errorf("Unsupported type: %T\n", reflect.TypeOf(arg))
}
Only slightly more verbose, but much easier to understand. But ultimate
Axel's first instinct is I think the right one -- just do the cast at
the call site.
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