Golang Debug Function

Question

Coming from shell programming, where i used a lot such function:

log_action() {
case "${1}" in
'ERROR')
    EXIT_CODE="${3}"
    echo "[${1}] | $(date +"%T") | ${2} | Exiting (${EXIT_CODE})"
    exit ${EXIT_CODE};
;;
'WARNING')
    echo "[${1}] | $(date +"%T") | ${2} | Line: (${3})"
;;
'DEBUG')
    if [[ ${DEBUG} -eq "1" ]]; then {
    echo "[${1}] | $(date +"%T") | ${2} | ${3}"
    }; fi
;;
*)
    echo "[${1}] | $(date +"%T") | ${2} | ${3}"
;;
esac
}


log_action "WARNING" "Cannot Connect to MySQL Database" "${LINENO}")

Now, i started to learn golang and will like to convert all bash scripts to go. So, I need the same function to use in golang, i tried the following:

func logHandler(t string, e string, l string) {
    switch t {
    case "warning":
        fmt.Println("WARNING")
    case "error":
        fmt.Println("ERROR")
    case "debug":
        fmt.Println("DEBUG |", e, l)
    }
}

logHandler("debug", "Test Function", "LineNumber")

but i don't know how to get the current linenumber variable (LineNumber) when calling logHandler function and pass it to the function as string or as int.

Also, is there any way to run a go script in trace mode like in bash option: set -o xtrace?

I'm just a beginner so if i'm doing something wrong please point me to the right direction. Thank You.

"any way to run a go script" no such thing. Go is not a scripting language. Go is only executable compiled down to a complete native binary. Trying to write Go programs like bash scripts (or anything else besides Go) will only lead to frustration. — Adrian
– Adrian, Commented Jul 17, 2018 at 20:40

Mihailo · Accepted Answer · 2018-07-17 21:26:03Z

3

Here's one elegant way you can do it.

We'll be using the runtime package, here's how:

package main

import (
    "fmt"
    "runtime"
)

func main() {
    logHandler("warning", "Test Function")
    logHandler("error", "Test Function")
    logHandler("debug", "Test Function")
}

func logHandler(t, e string) {
    switch t {
    case "warning":
        fmt.Println("WARNING |", e)
    case "error":
        fmt.Println("ERROR   |", e)
    case "debug":
        // 0 = This function
        // 1 = Function that called this function
        _, fn, line, _ := runtime.Caller(1)
        fmt.Printf("DEBUG   | %s:%d | %v\n", fn, line, e)
    }
}

Outputs:

WARNING | Test Function
ERROR   | Test Function
DEBUG   | /home/runner/main.go:11 | Test Function

Working example link

You could basically do this for all of them (warning and debug)

If you're interested here's some additional reading regarding the runtime package.

Inspired by this great answer from OneOfOne.

edited Jul 17, 2018 at 21:26

answered Jul 17, 2018 at 20:54

Mihailo

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3 Comments

Ilie Soltanici Over a year ago

Mihailo, your solution is very close to what I'm looking for. Just, by using this method I'm getting the line number inside the logHandler function, but what i'm looking for - is to get it from the main function, so in your example it actually should be number '11' instead of '23'.

Ilie Soltanici Over a year ago

Mihailo, Great!, that's exactly what i'm looking for. Thank you a lot!

Mihailo Over a year ago

Great! Glad I could help.

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