如何在 Go 中设置和访问“全局”记录器？

Question

我确信我遗漏了一些简单的基本问题，我是新手。假设我不想使用默认记录器，如何设置记录器以便它可以在函数之间共享？logissue.gopackage mainimport (  "fmt"  "github.com/pkg/errors"  "log"  "os")var dlog log.Loggerconst logfile string = "killer.log"const logprefix string = "LOGTEST: "func setupLogger(filename, prefix string) (*log.Logger, error) {  out, err := os.OpenFile(filename, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)  if err != nil {    return nil, errors.Wrap(err, "can't open logfile for writing")  }  return log.New(out, prefix, log.LstdFlags), nil}func uselog() error {  fmt.Printf("%T\n", dlog)  dlog.Printf("Hello")            ///// < Here is the issue  return nil}func main() {  dlog, err := setupLogger(logfile, logprefix)  if err != nil {    fmt.Printf("%+v", err)  }  dlog.Printf("test from main")  uselog()}stdoutlog.Loggerpanic: runtime error: invalid memory address or nil pointer dereference[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x10970b8]goroutine 1 [running]:log.(*Logger).Output(0x116dd00, 0x2, 0xc000016106, 0x5, 0x0, 0x0)    /usr/local/go/src/log/log.go:172 +0x1e8log.(*Logger).Printf(0x116dd00, 0x10c9202, 0x5, 0x0, 0x0, 0x0)    /usr/local/go/src/log/log.go:179 +0x7emain.uselog(0xc000088050, 0x10ca43b)    /Users/sequoia/learning/Ex_Files_Go_EssT/Exercise Files/logissue.go:25 +0xc4main.main()    /Users/sequoia/learning/Ex_Files_Go_EssT/Exercise Files/logissue.go:35 +0xeeexit status 2killer.logLOGTEST: 2019/02/17 18:25:12 test from main

Answer 1

因此，首先，根据您上面的代码，您尝试设置一个带有指针记录器的非指针记录器，但该指针记录器不起作用。其次，您在设置 dlog 时使用 := ，它在您的 main 方法中创建一个作用域变量，而不是设置您的全局变量

Answer 2

我试过这个：

import (

    "fmt"

    "github.com/pkg/errors"

    "log"

    "os"

)

const logfile string = "killer.log"

const logprefix string = "LOGTEST: "

var DLog *log.Logger

func setupLogger(filename, prefix string) {

    var err error

    out, err := os.OpenFile(filename, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)

    if err != nil {

        log.Fatal( nil, errors.Wrap(err, "can't open logfile for writing"))

    }

    DLog=log.New(out, prefix, log.LstdFlags)

    fmt.Println("Log object: ",DLog)

}

func uselog() error {

    DLog.Print("Hello") ///// < Here is the issue

    DLog.Print("I have something standard to say")

    fmt.Println("I am done")

    return nil

}

func main() {

    setupLogger(logfile, logprefix)

    DLog.Printf("test from main")

    uselog()

}