how to get slice type of a type?

[Davies Liu]

Hi, nuts:

I try to get reflect.MakeSlice() according to the element Type, how to ?

If in reflect package, It's like this:

func MakeTypeSlice(typ Type, len, cap int) Value {

     // check typ, len and cap

    var x []byte

    s := (*reflect.SliceHeader)(unsafe.Pointer(&x))

    s.Data = uintptr(unsafe_NewArray(typ, cap))

    s.Len = len

    s.Cap = cap

    

    styp := arrayType{} // TODO

    return Value{styp, unsafe.Pointer(&x), flagIndir | flag(Slice) << flagKindShift)}

}

How can i archive this outside of reflect package ?

--
 - Davies

[Rémy Oudompheng]

Le 1 avril 2012 10:13, Davies Liu <davie...@gmail.com> a écrit :
> Hi, nuts:
>
> I try to get reflect.MakeSlice() according to the element Type, how to ?
>
> If in reflect package, It's like this:
>
> func MakeTypeSlice(typ Type, len, cap int) Value {
>      // check typ, len and cap
>
>     var x []byte
>     s := (*reflect.SliceHeader)(unsafe.Pointer(&x))
>     s.Data = uintptr(unsafe_NewArray(typ, cap))
>     s.Len = len
>     s.Cap = cap
>
>     styp := arrayType{} // TODO

There's some work needed to do that while perserving type safety:
* two successive calls must return Values of the same Type
* two concurrent calls must return Values of the same Type
* a call to MakeSliceOf(TypeOf(MyType)) must return a Value of the
same type as ValueOf([]MyType{}).

Issue number 2339 tracks this kind of request:
http://code.google.com/p/go/issues/detail?id=2339

Rémy.