Re: [go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
Yes, trailing zero-size elements affect the size.
https://play.golang.org/p/Ox0FJX3C5V
https://github.com/golang/go/commit/6f07ac2f280847ee0346b871b23cab90869f84a4
On Tue, 2017-07-11 at 20:34 -0700, Rader wrote:
> I found the position of `[0]byte` in the struct matters.
> type bar2 struct {
> A int
> _ [0]byte
> }
>
> differs from
>
> type bar3 struct {
> _ [0]byte
> A int
> }
>
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Re: [go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
Both are used.
On Wed, 2017-07-12 at 11:43 +, Matthew Zimmerman wrote:
> Why not use struct{}? Is what is recommended for maps to notate a
> set
> (only the keys mean something).
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Re: [go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
Can you do a test to see if there's a performance difference? -- 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.
Re: [go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
sure you can. no memory space difference.
On Wednesday, July 12, 2017 at 7:44:47 PM UTC+8, Matthew Zimmerman wrote:
>
> Why not use struct{}? Is what is recommended for maps to notate a set
> (only the keys mean something).
>
> https://play.golang.org/p/fxtEWejqdh
>
> On Tue, Jul 11, 2017, 11:34 PM Rader
> wrote:
>
>> I found the position of `[0]byte` in the struct matters.
>> type bar2 struct {
>> A int
>> _ [0]byte
>> }
>>
>> differs from
>>
>> type bar3 struct {
>> _ [0]byte
>> A int
>> }
>>
>>
>>
>> see the full example
>>
>>
>>
>> On Wednesday, July 12, 2017 at 10:44:04 AM UTC+8, Rader wrote:
>>>
>>> they both have the same size, eg. following structs bar and bar2 both
>>> take 16 bytes memory on a x64 machine.
>>>
>>> package main
>>>
>>> import (
>>> "fmt"
>>> "unsafe"
>>> )
>>>
>>> type bar struct {
>>> A int
>>> _ bool
>>> }
>>>
>>> type bar2 struct {
>>> A int
>>> _ [0]byte
>>>
>>> }
>>>
>>> func main() {
>>> bar := bar{}
>>> bar2 := bar2{}
>>> fmt.Printf("size of bar:%v\n", unsafe.Sizeof(bar))
>>> fmt.Printf("size of bar2:%v\n", unsafe.Sizeof(bar2))
>>> }
>>>
>>>
>>>
>>> On Thursday, July 6, 2017 at 11:45:30 AM UTC+8, kortschak wrote:
On Wed, 2017-07-05 at 17:26 -0700, rsr via golang-nuts wrote:
> type bar struct {
>A int
>_ bool
> }
or `type bar struct { A int; _ [0]byte }` to avoid the additional byte
use.
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Re: [go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
Why not use struct{}? Is what is recommended for maps to notate a set
(only the keys mean something).
https://play.golang.org/p/fxtEWejqdh
On Tue, Jul 11, 2017, 11:34 PM Rader wrote:
> I found the position of `[0]byte` in the struct matters.
> type bar2 struct {
> A int
> _ [0]byte
> }
>
> differs from
>
> type bar3 struct {
> _ [0]byte
> A int
> }
>
>
>
> see the full example
>
>
>
> On Wednesday, July 12, 2017 at 10:44:04 AM UTC+8, Rader wrote:
>>
>> they both have the same size, eg. following structs bar and bar2 both
>> take 16 bytes memory on a x64 machine.
>>
>> package main
>>
>> import (
>> "fmt"
>> "unsafe"
>> )
>>
>> type bar struct {
>> A int
>> _ bool
>> }
>>
>> type bar2 struct {
>> A int
>> _ [0]byte
>>
>> }
>>
>> func main() {
>> bar := bar{}
>> bar2 := bar2{}
>> fmt.Printf("size of bar:%v\n", unsafe.Sizeof(bar))
>> fmt.Printf("size of bar2:%v\n", unsafe.Sizeof(bar2))
>> }
>>
>>
>>
>> On Thursday, July 6, 2017 at 11:45:30 AM UTC+8, kortschak wrote:
>>>
>>> On Wed, 2017-07-05 at 17:26 -0700, rsr via golang-nuts wrote:
>>> > type bar struct {
>>> >A int
>>> >_ bool
>>> > }
>>>
>>>
>>> or `type bar struct { A int; _ [0]byte }` to avoid the additional byte
>>> use.
>>>
>>> --
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Re: [go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
I found the position of `[0]byte` in the struct matters.
type bar2 struct {
A int
_ [0]byte
}
differs from
type bar3 struct {
_ [0]byte
A int
}
see the full example
On Wednesday, July 12, 2017 at 10:44:04 AM UTC+8, Rader wrote:
>
> they both have the same size, eg. following structs bar and bar2 both take
> 16 bytes memory on a x64 machine.
>
> package main
>
> import (
> "fmt"
> "unsafe"
> )
>
> type bar struct {
> A int
> _ bool
> }
>
> type bar2 struct {
> A int
> _ [0]byte
>
> }
>
> func main() {
> bar := bar{}
> bar2 := bar2{}
> fmt.Printf("size of bar:%v\n", unsafe.Sizeof(bar))
> fmt.Printf("size of bar2:%v\n", unsafe.Sizeof(bar2))
> }
>
>
>
> On Thursday, July 6, 2017 at 11:45:30 AM UTC+8, kortschak wrote:
>>
>> On Wed, 2017-07-05 at 17:26 -0700, rsr via golang-nuts wrote:
>> > type bar struct {
>> >A int
>> >_ bool
>> > }
>>
>>
>> or `type bar struct { A int; _ [0]byte }` to avoid the additional byte
>> use.
>>
>>
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Re: [go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
they both have the same size, eg. following structs bar and bar2 both take
16 bytes memory on a x64 machine.
package main
import (
"fmt"
"unsafe"
)
type bar struct {
A int
_ bool
}
type bar2 struct {
A int
_ [0]byte
}
func main() {
bar := bar{}
bar2 := bar2{}
fmt.Printf("size of bar:%v\n", unsafe.Sizeof(bar))
fmt.Printf("size of bar2:%v\n", unsafe.Sizeof(bar2))
}
On Thursday, July 6, 2017 at 11:45:30 AM UTC+8, kortschak wrote:
>
> On Wed, 2017-07-05 at 17:26 -0700, rsr via golang-nuts wrote:
> > type bar struct {
> >A int
> >_ bool
> > }
>
>
> or `type bar struct { A int; _ [0]byte }` to avoid the additional byte
> use.
>
>
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[go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
Hi rob
Thanks for your response. I didn't know that trick, but it seems to me a
little bit ugly to guard fields that way. I will stick to named
initialisations and write it as a policy into the style guide.
Cheers
Am Donnerstag, 6. Juli 2017 02:26:27 UTC+2 schrieb rob rodgers:
>
> for some of our sensitive structures that are tricky and have multiple
> fields of the same type, there is a trick you can use:
>
> type bar struct {
>A int
>_ bool
> }
>
> see https://play.golang.org/p/rFKGoKq-S9
>
>
>
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Re: [go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
On Wed, 2017-07-05 at 17:26 -0700, rsr via golang-nuts wrote:
> type bar struct {
> A int
> _ bool
> }
or `type bar struct { A int; _ [0]byte }` to avoid the additional byte use.
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[go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
for some of our sensitive structures that are tricky and have multiple
fields of the same type, there is a trick you can use:
type bar struct {
A int
_ bool
}
see https://play.golang.org/p/rFKGoKq-S9
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[go-nuts] Re: Named or unnamed struct initialisation? What is best practice?
Okay thanks, as I supposed. Personally i used always named initialisation despite of the overhead, but sometimes I feel the urge to use the short unamed initialisation. ;-) Am Mittwoch, 5. Juli 2017 07:41:04 UTC+2 schrieb Tamás Gulácsi: > > Named. -- 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.
