Ethereum Cookbook

How to do it...

Follow these steps to create and emit events from the contract:

1. Events are declared with the event keyword. The following example creates an event with three parameters:

event Transfer(    address _from,    address _to,    uint _value);

2. Events are emitted/logged with the emit keyword:

function transfer(address _to, uint _value) public {    // Function body    emit Transfer(msg.sender, _to, _value);}

3. Up to three parameters can be indexed in an event. We can use indexed parameters to filter events based on requirements. If arrays, strings, or bytes are used as indexed arguments, the Keccak-256 hash of it is stored as a topic:

event Transfer(    address indexed _from,    address indexed _to,    uint _value);

4. By default, all events will have ...