xray - look through your golang objects

Introduction

Trouble shooting a project isn't easy, especially when pointers are being used. It's often difficult to get an idea on an object in runtime. Xray is designed to parse runtime objects, and help user to analyze the objects. The accompany dot package, as an example, will generate a dot representation of the object so user could easilly visualize the object.

Examples

Default formatted printer

Typically, user could print their objects in string format:

package main

import "fmt"

type test struct {
	ptr *string
	arr []int
	m   map[string]int
}

func main() {
	str := "deadbeef"
	object := test{
		ptr: &str,
		arr: []int{1, 2, 3},
		m:   map[string]int{"foo": 1, "bar": 2},
	}
	fmt.Printf("object:\n%#v\n", object)
}

Then this is what you got:

object:
main.test{ptr:(*string)(0xc000010200), arr:[]int{1, 2, 3}, m:map[string]int{"bar":2, "foo":1}}

It's not helpful when you want to reason about the pointers, and becomes messy when the struct becomes complicated.

Xray parsed object

By using xray, you can parse the golang object and generate a dot representation of it, here's the snipple:

package main

import (
	"fmt"
	"github.com/hanlins/xray"
	"github.com/hanlins/xray/dot"
)

type test struct {
	ptr *string
	arr []int
	m   map[string]int
}

func main() {
	str := "deadbeef"
	object := test{
		ptr: &str,
		arr: []int{1, 2, 3},
		m:   map[string]int{"foo": 1, "bar": 2},
	}

	s := xray.NewScanner(nil)
	nodeCh := s.Scan(object)
	g, _ := dot.Draw(dot.NewGraphInfo(s), nodeCh, nil)
	fmt.Printf("dot object:\n%s\n", g)
}

You can use the dot binary (need to install graphviz package) locally or some online generator (e.g. viz-js) to generate an image, and use it in your report. Here's the generated image: