Golang Stack Traces

https://www.ardanlabs.com/blog/2015/01/stack-traces-in-go.html

package main

func main() {
    slice := make([]string, 2, 4)
    Example(slice, "hello", 10)
}

func Example(slice []string, str string, i int) {
    panic("Want stack trace")
}

You will get a stack track like this:

01 goroutine 1 [running]:
02 main.Example(0x2080c3f50, 0x2, 0x4, 0x425c0, 0x5, 0xa)
           /Users/bill/Spaces/Go/Projects/src/github.com/goinaction/code/
           temp/main.go:9 +0x64
03 main.main()
           /Users/bill/Spaces/Go/Projects/src/github.com/goinaction/code/
           temp/main.go:5 +0x85

Line main.Example(0x2080c3f50, 0x2, 0x4, 0x425c0, 0x5, 0xa) is the source code Example(slice, "hello", 10) with parameters showing six hexadecimal. The key to understanding how the values do match up with the parameters requires knowing the implementation for each parameter type.

In the above example, the first parameter is a slice of strings. A slice is a reference type in Go. This means the value for a slice is a header value with a pointer to some underlying data. In the case of a slice, the header value is a three word structure that contains a pointer to an underlying array, the length of the slice and the capacity.

The second parameter is a string. A string is also a reference type but this header value is immutable. The header value for a string is declared as a two word structure that contains a pointer to an underlying byte array and the length of the string.