On Saturday, August 27, 2016 at 1:36:53 PM UTC+8, Ian Lance Taylor wrote: > > On Fri, Aug 26, 2016 at 9:46 PM, T L <tapi...@gmail.com <javascript:>> > wrote: > > > >> "You are suggesting that there is an extra rule to forbids converting > []T1 > >> to > > []T2 when T1 and T2 have the same underlying representation." > > > > No. I understand []T1 can't be converted to []T2 when T1 and T2 have > > different underlying representation. > > > > Ok, the alternative of my question is: why []T2 and []T1 have different > > underlying representations when T2 and T1 have the same underlying > > representation? > > They don't. > > If T2 and T1 have the same underlying representation, then []T2 and > []T1 have the same underlying representation. > > > >> "despite the overall prohibition on converting []T1 to > > []T2, you are permitted to convert them exactly when T1 and T2 have > > the same underlying representation. That rule is much more complex > > than the current rule. It means that people reading Go code have to > > understand when T1 and T2 have the same representation." > > > > So you mean there is no implementation obstacles to allow converting > []Age > > to []int? > > That is correct. > > > > The prohibition is just to make people less confused. > > I would say that it is to make the language simpler. There are fewer > things that people learning the language need to understand. > > > > But the current prohibition make me confused, may I am not a typical > gopher. > > Why does it make you confused? > > On a 64-bit system, the types "int" and "int64" have the same > representation. They are both 64-bit signed integers. Does it > confuse you that Go rejects > > var v int = int64(1) >
I don't think an int64 value can be converted to an int value is for they have the same underlying type. In fact, an int8 value can also be converted to an int value. "Number values can be converted to values of other number types" is totally an exception for the conversion rule. This has nothing related to the underlying types. > > ? > > If that does not confuse you, then the fact Go does not permit > assigning from []Age to []int should not confuse you. It is the same > kind of thing: in Go, different types are different. > > Ian > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
