Events

Orbs contract events give you the ability to log information into the blockchain that is stored as part of the receipt block.

Here is a simple contract that emits an event. We will go over it in details:

package main

import (
    "github.com/orbs-network/orbs-contract-sdk/go/sdk/v1"
    "github.com/orbs-network/orbs-contract-sdk/go/sdk/v1/events"
    "github.com/orbs-network/orbs-contract-sdk/go/sdk/v1/state"
)

var PUBLIC = sdk.Export(giveBirth)
var SYSTEM = sdk.Export(_init)
var EVENTS = sdk.Export(BabyBorn)

func BabyBorn(name string, weight uint32) {}

func _init() {
    state.WriteUint64([]byte("some_data"), 1)
}

func giveBirth(name string) {
    events.EmitEvent(BabyBorn, name, uint32(3))
}

Using the Events API require you first to import it:

import (
    "github.com/orbs-network/orbs-contract-sdk/go/sdk/v1/events"
)

Next, we export the event:

var EVENTS = sdk.Export(BabyBorn)

Then we declare it as an empty function. Note that the empty bracers are required ({}):

func BabyBorn(name string, weight uint32) {}

When the function giveBirth(name string) is called, we want the event to be emitted, so we call the events.EmitEvent function:

events.EmitEvent(BabyBorn, name, uint32(3))

The arguments are a pointer to the event function (which is also exported) and the event arguments.