Macro cbk_new_callback_func 

macro_rules! cbk_new_callback_func {
    ($func_name:ident, $arg_name:ident, $body:block) => { ... };
}

This macro generates a function that take a reference to a Box<dyn Any> as an argument and return nothing. The function body ($body) is the code that will be execute when the callback is trigger.

Usage

Use for defining functions required to create a Callback object,

Parameters

• func_name: An identifier (ident) representing the generated function name.
• arg_name: An identifier (ident) representing the function argument name.
• body: A block (block) containing the function implementation.

Example

// A callback function that accept a u32 an print it out.
cbk_new_callback_func!(print_num, arg, {
   println!("{}", cbk::cast_arg::<u32>(arg)?);
   Ok(())
});