Macro workflow_wasm::callback::callback

callback!() { /* proc-macro */ }

creates a Callback instance by inspecting a given closure signature

// include dependencies
use workflow_wasm::prelude::*;

Warning: the callback macro expects to receive a closure as an argument
and will use this closure’s signature to determine which Callback binding function
to use.  However, if you declare a closure as a variable and then try to pass
it to the callback macro, the macro will fail with an error as follows:
“closure is expected to take 1 argument”

• If passing closure as variable, it will accept only 1 argument:

let closure_as_variable = |value:bool|{
    ...
};
let callback = callback!(closure_as_variable);

The above code will create callback like this:

let callback = Callback::new(closure_as_variable);

• Examples of incorrect use:

// 2 arguments
let closure_as_variable = |arg1:bool, arg2:u16|{
    //...
};
let callback = callback!(closure_as_variable);

// no arguments
let closure_as_variable = ||{
    //...
};
let callback = callback!(closure_as_variable);

• If you have closure variable with more or less than 1 argument, you can use on the the following direct methods:

  • Callback::new_with_args_0
  • Callback::new_with_args_1
  • Callback::new_with_args_2
  • Callback::new_with_args_3
  • Callback::new_with_args_4
  • Callback::new_with_args_5
  • Callback::new_with_args_6
  • Callback::new_with_args_7
  • Callback::new_with_args_8

• A closure supplied directly to the callback macro can accept 0-8 arguments:

  let callback = callback!(|value:bool|{
      //
  });
  

  Output will be as follows:

  let callback = Callback::new_with_args_1(|value:bool|{
      //
  });
  

• Example of a closure with 2 arguments:

  let callback = callback!(|arg1:u16, value:bool|{
      //
  });
  

  Output will be as follows:

  let callback = Callback::new_with_args_2(|arg1:u16, value:bool|{
     //
  });