StefanosPs/dumper

Go Dumper

When debugging Go code, being able to dump values with nice formatting and colors can go a long way:

package main

import (
    "time"

    . "github.com/symfony-cli/dumper"
)

func main() {
    now := time.Now().Local()
    Dump(now)
}

Output:

time.Time{{
  wall: 507838786, // uint64
  ext: 63649250679, // int64
  loc: &time.Location { // (0x0014c3a0)
    name: "",
    zone: nil, // []time.zone
    tx: nil, // []time.zoneTrans
    cacheStart: 0, // int64,
    cacheEnd: 0, // int64,
    cacheZone: nil, // &time.zone
  },
}

Custom Dumpers

Implement the Dumpable interface on your types to take control of how your type is dumped:

type Dumpable interface {
    Dump(State)
}

Use the available helpers on the State object to write your custom dump. Alternatively, you can write directly to the provided stream. In both cases, your type name (and eventually the pointer comment) will be automatically added.

Read he test suite for some examples.

Another alternative, useful for package you don't maintain is to register a function of type DumpFunc:

func init() {
    RegisterCustomDumper(http.Request{}, dumpHttpRequest)
}

func dumpHttpRequest(s State, v reflect.Value) {
    for _, f := range []string{"Status", "Proto"} {
        s.DumpStructField(f, v.FieldByName(f))
    }
    s.AddComment("Hello World!")
}