Attribute Macro event

#[event]

Implements the necessary traits for a struct to be emitted as an event from a contract.

By default, a signature topic will be generated for the event. This allows consumers to filter and identify events of this type. Marking an event with anonymous means no signature topic will be generated or emitted. Custom signature topic can be specified with signature_topic = <32 byte hex string>.

signature_topic and anonymous are conflicting arguments.

Examples

#[ink::event]
pub struct MyEvent {
    pub field: u32,
    #[ink(topic)]
    pub topic: [u8; 32],
}

// Setting `anonymous` means no signature topic will be emitted for the event.
#[ink::event(anonymous)]
pub struct MyAnonEvent {
    pub field: u32,
    #[ink(topic)]
    pub topic: [u8; 32],
}
// Setting `signature_topic = <hex_string>` specifies custom signature topic.
#[ink::event(
    signature_topic = "1111111111111111111111111111111111111111111111111111111111111111"
)]
pub struct MyCustomSignatureEvent {
    pub field: u32,
    #[ink(topic)]
    pub topic: [u8; 32],
}