Is it possible to convert []A to []B, or []*A to []*B ?

[nicolas...@gmail.com]

Having "type A int" and "type B A", I try to convert []A to []B, but it fails.

It seems that Go doesn't allow such conversion, notwithstanding the memory layout is the same for []A and []B ?

So, I must convert each element to the target type into a new slice, as in the two following snippets ?

Conversion []A to []B:
http://play.golang.org/p/BXHg66NKUs

Conversion []*A to []*B:
http://play.golang.org/p/jUoOirBybN

[Brad Fitzpatrick]

http://golang.org/doc/faq#convert_slice_of_interface

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[Erwin]

it can be done using unsafe.Pointer, see

http://play.golang.org/p/PbhbnlTN_v

[chris dollin]

On 26 June 2014 19:42, Erwin <snes...@gmail.com> wrote:

it can be done using unsafe.Pointer, see

http://play.golang.org/p/PbhbnlTN_v

You can also keep warm by setting fire to the carpet.

Using unsafe to do a type conversions is an open opportunity

for error.

One suspects that there as an earlier design decision leading
the code up the garden path.

Chris

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Chris "allusive" Dollin

[Erwin]

Surely caution is needed, but here it is actually safe to do so. 

[Jesse McNelis]

On Fri, Jun 27, 2014 at 4:56 AM, Erwin <snes...@gmail.com> wrote:
> Surely caution is needed, but here it is actually safe to do so.

As long as everyone that works on this code knows that A and B need to
always be the same size and that you need to be careful with what you
assign to the variable 'b' and that the size of slices doesn't change
in a type specific way sometime in the future or on some different
implementation.

I'm sure the newbie asking this question knows all of this.

[chai2010]

This is a example:

http://godoc.org/github.com/chai2010/gopkg/builtin#example-Slice

convert []A to []B:

b := Slice([]A{1,2}, reflect.TypeOf([]B(nil))).([]B)

And sizeof(A) and sizeof(B) don't need the same size.

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