Attribute Macro brush_lang::modifier_definition

#[modifier_definition]

This macro only checks that some free-standing function satisfies a set of rules.

Rules:

• First argument should not be self.
• First argument must be a reference to a type instance: &T. In most cases it’s the instance of contract.
• Second argument is function’s body(this function contains the main code of method attached to the modifier). The type must be Fn(&T), FnMut(&T) or FnOnce(&T).
• Every next argument should not be references to object. Because modifier allows only to pass arguments by value(Modifier will pass the clone of argument).
• The return type of body function(second argument) must be the same as the return type of modifier.

Example: Definition

#[derive(Default)]
struct Contract {
    initialized: bool,
}

#[brush::modifier_definition]
fn once<BodyFn: FnOnce(&mut Contract)>(instance: &mut Contract, body: BodyFn, _example_data1: u8, _example_data2: u8) {
    assert!(!instance.initialized, "Contract is already initialized");
    body(instance);
    instance.initialized = true;
}