How to Emit Events from Precompiles

integration intermediate

A quick guide on using the utils.EmitEvent helper to generate EVM logs.

Prerequisites

Go
Maroo Precompile Architecture

Understanding Arguments

The args variadic parameter in EmitEvent must contain both indexed (topics) and non-indexed (data) arguments in the exact order they appear in the Solidity event definition.

event MyEvent(uint256 indexed id, string name);

Note: For the event above, you must pass `id` (uint256) first, then `name` (string).

Handling Errors

Always check the returned error. Common errors include EventNotFound (typo in name) or ArgCountMismatch.

if err := utils.EmitEvent(...); err != nil {
    // Log internal error, but maybe return a generic error to EVM to avoid leaking implementation details
    return nil, err
}