Re: [go-nuts] Re: Unexpected behavior with panic/defer/recover
There is also one additional caveat (not for your example, but just in case
you stumble upon it): recover must be called *from a deferred
function, *meaning
"defer recover()" won't work either. You *always* need to wrap recover in a
function and that function *always* needs to be directly defer'd.
On Wed, Mar 29, 2017 at 4:21 AM, T L wrote:
> http://www.tapirgames.com/blog/golang-panic-recover-mechanism
>
>
> On Wednesday, March 29, 2017 at 6:48:52 AM UTC+8, Stefan Engstrom wrote:
>>
>> Playing with recovery from a panic - this code does what i expect: (
>> https://play.golang.org/p/p5KvOYc1sx)
>>
>> package main
>>
>> import "fmt"
>>
>> func main() {
>> defer func() {
>> fmt.Println("main:",recover())
>> }()
>> a()
>> }
>>
>> func a() {
>> panic("yikes")
>> }
>>
>> Results in:
>>
>> main: yikes
>>
>>
>>
>>
>> A simpler version without the closure doesn't catch the panic: (
>> https://play.golang.org/p/0ICqqdi2kL)
>>
>> package main
>>
>> import "fmt"
>>
>> func main() {
>> defer fmt.Println("main:",recover())
>> a()
>> }
>>
>> func a() {
>> panic("yikes")
>> }
>>
>> Produces:
>>
>> main:
>> panic: yikes
>>
>> goroutine 1 [running]:
>> main.a()
>> /tmp/sandbox638763687/main.go:11 +0x60
>> main.main()
>> /tmp/sandbox638763687/main.go:7 +0x100
>>
>>
>> I see the same behavior on linux/amd64 go1.8
>>
>> Any idea why the second version fails to catch that panic?
>>
>> Thanks,
>>
>> Stefan
>>
>> --
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[go-nuts] Re: Unexpected behavior with panic/defer/recover
http://www.tapirgames.com/blog/golang-panic-recover-mechanism
On Wednesday, March 29, 2017 at 6:48:52 AM UTC+8, Stefan Engstrom wrote:
>
> Playing with recovery from a panic - this code does what i expect: (
> https://play.golang.org/p/p5KvOYc1sx)
>
> package main
>
> import "fmt"
>
> func main() {
> defer func() {
> fmt.Println("main:",recover())
> }()
> a()
> }
>
> func a() {
> panic("yikes")
> }
>
> Results in:
>
> main: yikes
>
>
>
>
> A simpler version without the closure doesn't catch the panic: (
> https://play.golang.org/p/0ICqqdi2kL)
>
> package main
>
> import "fmt"
>
> func main() {
> defer fmt.Println("main:",recover())
> a()
> }
>
> func a() {
> panic("yikes")
> }
>
> Produces:
>
> main:
> panic: yikes
>
> goroutine 1 [running]:
> main.a()
> /tmp/sandbox638763687/main.go:11 +0x60
> main.main()
> /tmp/sandbox638763687/main.go:7 +0x100
>
>
> I see the same behavior on linux/amd64 go1.8
>
> Any idea why the second version fails to catch that panic?
>
> Thanks,
>
> Stefan
>
>
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[go-nuts] Re: Unexpected behavior with panic/defer/recover
That's kind of expected behavior , "*1. A deferred function's arguments are
evaluated when the defer statement is evaluated." *
refer to https://blog.golang.org/defer-panic-and-recover
On Wednesday, March 29, 2017 at 9:48:52 AM UTC+11, Stefan Engstrom wrote:
>
> Playing with recovery from a panic - this code does what i expect: (
> https://play.golang.org/p/p5KvOYc1sx)
>
> package main
>
> import "fmt"
>
> func main() {
> defer func() {
> fmt.Println("main:",recover())
> }()
> a()
> }
>
> func a() {
> panic("yikes")
> }
>
> Results in:
>
> main: yikes
>
>
>
>
> A simpler version without the closure doesn't catch the panic: (
> https://play.golang.org/p/0ICqqdi2kL)
>
> package main
>
> import "fmt"
>
> func main() {
> defer fmt.Println("main:",recover())
> a()
> }
>
> func a() {
> panic("yikes")
> }
>
> Produces:
>
> main:
> panic: yikes
>
> goroutine 1 [running]:
> main.a()
> /tmp/sandbox638763687/main.go:11 +0x60
> main.main()
> /tmp/sandbox638763687/main.go:7 +0x100
>
>
> I see the same behavior on linux/amd64 go1.8
>
> Any idea why the second version fails to catch that panic?
>
> Thanks,
>
> Stefan
>
>
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