Events

Events allow for the output of information during contract execution. Such data can later on be consumed by other entities outside of StarkNet.

The difference between Storage- and Event data is that Storage data can be used from within Smart Contracts whereas Event data cannot.

Events are implemented via functions decorated with the @event annotation. Calling emit on such functions will output the Event data.

Example

%lang starknet

# The `@event` annotation turns this function into an Event emitter.
@event
func logger(number : felt):
end

@external
func get_number{syscall_ptr : felt*, range_check_ptr}() -> (number : felt):
    let number = 42

    # Calling `emit` will output the Event data (the number 42 in our case).
    logger.emit(number)

    return (number)
end