On Sat, Dec 31, 2016 at 3:26 AM, Uwe Dauernheim <u...@dauernheim.net> wrote:
> It seem a float64 of value 0.0 as types interface{} can't be compared equal
> to 0 in an exhaustive case clause type list, but can be compared equal in
> almost any other scenario.
>
> https://play.golang.org/p/t2u2GGp565
>
> I find this unexpected. Could someone explain how case clause type lists in
> type assertions work?
> The language specification states:
>
>> In clauses with a case listing exactly one type, the variable has that
>> type; otherwise, the variable has the type of the expression in the
>> TypeSwitchGuard.
>
> In the provided playground is no TypeSwitchGuard given, so this rule should
> not affect behaviour.
switch g := f.(type) {
case int, int8, int16, int32, int64, uint, uint8, uint16, uint32,
uint64, float32, float64:
//g is of type interface{}
}
"the expression in the TypeSwitchGuard" is 'f' which is of type
interface{} in this case. Thus 'g' has the type interface{} within the
case.
The comparison 'g == 0' is false because 'g' contains a float64 and 0
is an int.
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