Is it possible get information about caller function in Golang?

Solution 1:

You can use runtime.Caller for easily retrieving information about the caller:

func Caller(skip int) (pc uintptr, file string, line int, ok bool)

Example #1: Print caller file name and line number: https://play.golang.org/p/cdO4Z4ApHS

package main

import (
    "fmt"
    "runtime"
)

func foo() {
    _, file, no, ok := runtime.Caller(1)
    if ok {
        fmt.Printf("called from %s#%d\n", file, no)
    }
}

func main() {
    foo()
}

Example #2: Get more information with runtime.FuncForPC: https://play.golang.org/p/y8mpQq2mAv

package main

import (
    "fmt"
    "runtime"
)

func foo() {
    pc, _, _, ok := runtime.Caller(1)
    details := runtime.FuncForPC(pc)
    if ok && details != nil {
        fmt.Printf("called from %s\n", details.Name())
    }
}

func main() {
    foo()
}

Solution 2:

expanding on my comment, here's some code that returns the current func's caller

import(
    "fmt"
    "runtime"
)

func getFrame(skipFrames int) runtime.Frame {
    // We need the frame at index skipFrames+2, since we never want runtime.Callers and getFrame
    targetFrameIndex := skipFrames + 2

    // Set size to targetFrameIndex+2 to ensure we have room for one more caller than we need
    programCounters := make([]uintptr, targetFrameIndex+2)
    n := runtime.Callers(0, programCounters)

    frame := runtime.Frame{Function: "unknown"}
    if n > 0 {
        frames := runtime.CallersFrames(programCounters[:n])
        for more, frameIndex := true, 0; more && frameIndex <= targetFrameIndex; frameIndex++ {
            var frameCandidate runtime.Frame
            frameCandidate, more = frames.Next()
            if frameIndex == targetFrameIndex {
                frame = frameCandidate
            }
        }
    }

    return frame
}

// MyCaller returns the caller of the function that called it :)
func MyCaller() string {
        // Skip GetCallerFunctionName and the function to get the caller of
        return getFrame(2).Function
}

// foo calls MyCaller
func foo() {
    fmt.Println(MyCaller())
}

// bar is what we want to see in the output - it is our "caller"
func bar() {
    foo()
}

func main(){
    bar()
}

For more examples: https://play.golang.org/p/cv-SpkvexuM