On Mon, Jun 9, 2025 at 7:01 PM Zhaoxun Yan <yan.zhao...@gmail.com> wrote:
> Oh! Thank you Kurtis. So do you have a special Editor to inform you about > the functions? My current editor cannot even tell what type of variable a > go function would return, let alone parameter hints, etc. > I use a VIM plugin that talks to the https://pkg.go.dev/golang.org/x/tools/gopls tool. That makes it easy to jump to the definition of a function or other symbol and find all the places that use it. It is likely your editor can be configured to interact with that tool. > On Mon, Jun 9, 2025 at 1:50 PM Kurtis Rader <kra...@skepticism.us> wrote: > >> >> On Sun, Jun 8, 2025 at 9:35 PM Zhaoxun Yan <yan.zhao...@gmail.com> wrote: >> >>> it turned out to be an error misjudgement. The real line that caused >>> trouble is this: >>> s = er.Error()+string(out) >>> The error is gone after I changed it to this line : >>> s = fmt.Sprintf("%v %s", er, out) >>> >> >> The stdlib os.exec.Command() >> <https://pkg.go.dev/os/exec@go1.24.4#Command>function only returns a >> single value. Which should result in a compiler error since your program >> expects two values. I'm going to guess that you are calling a different >> function with that name which can return two values and the "er" return >> value can be nil. Which would result in the "er.Error()" call to >> dereference a nil value. So I think you have incorrectly diagnosed the >> cause of the problem. The first statement does not correctly handle "er" >> being nil. The "fmt.Sprintf()" correctly handles "er" being the nil value. >> >> >>> On Fri, Jun 6, 2025 at 6:29 PM Zhaoxun Yan <yan.zhao...@gmail.com> >>> wrote: >>> >>>> -------------------- >>>> panic: runtime error: invalid memory address or nil pointer dereference >>>> [signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x6646f2] >>>> >>>> goroutine 1 [running]: >>>> util.CommandArgs({0xc000093cb0?, 0x2?, 0xc000071380?}) >>>> /home/zxun/src/util/util.go:49 +0xf2 >>>> -------------------- >>>> This error occurred because package [main] uses a function called >>>> "CommandArgs" from my self-built package [util] with args in another >>>> package [conf] in the same directory. Package [util] got lost because it >>>> does not know where is package [conf] >>>> like this >>>> [util] /home/zxun/src/util.go >>>> [conf] /home/zxun/src/conf.go >>>> [main] /home/zxun/src/main.go... >>>> /home/zxun/src/go.mod: >>>> >>>> require( >>>> util v0.0.0 >>>> ... >>>> replace util => ../util >>>> >>>> The usage line in main.go: >>>> fmt.Println( util.CommandArgs([]string{conf.IreportExec, >>>> conf.IreportScript, "redis"}) ) >>>> >>>> util.CommandArgs: >>>> >>>> func CommandArgs(args []string) string{ >>>> if len(args) ==0{ >>>> return "args are empty！" >>>> } >>>> var s string >>>> if len(args) ==1{ >>>> out, er := exec.Command(args[0]).CombinedOutput() >>>> s = er.Error()+string(out) >>>> }else{ >>>> out, er := exec.Command(args[0],args[1:]...).CombinedOutput() >>>> s = er.Error()+string(out) >>>> fmt.Println(s) >>>> } >>>> return s >>>> } >>>> >>>> So is my analysis correct? I have not seen s printed yet, because s >>>> shall include "<nil>" at the beginning. I am using go1.18. If the cause is >>>> util package cannot access a variable in conf, is it possible to walk >>>> around by a deepcopy of the string array (which will be in package main)? >>>> >>>> Thanks in advance. >>>> >>> -- >>> 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. >>> To view this discussion visit >>> https://groups.google.com/d/msgid/golang-nuts/CADEX6_Wzy%3DPoqdXBNUqQ0tGYmQfacTq6A%2By58a5osDkKB-Z1yA%40mail.gmail.com >>> <https://groups.google.com/d/msgid/golang-nuts/CADEX6_Wzy%3DPoqdXBNUqQ0tGYmQfacTq6A%2By58a5osDkKB-Z1yA%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> >> -- >> Kurtis Rader >> Caretaker of the exceptional canines Junior and Hank >> > -- Kurtis Rader Caretaker of the exceptional canines Junior and Hank -- 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. To view this discussion visit https://groups.google.com/d/msgid/golang-nuts/CABx2%3DD-_MxcMch21H-UhOX_N8Wf2A-8Gtb-WJ1DXqkh5YBAEGQ%40mail.gmail.com.
