Vector of mixed closures types

[autumn crypt]

Hi folks !

I have a problem / question with generics. I don't even know if what i'm trying to do is doable....

I have a vector of structs that contain a closure :

pub struct Handling<'a, E>{
    pub handler: Box<dyn FnMut(&mut Arg) -> Result<(), E> + 'a>,
}

pub type Handlers<'a, E> = Vec<Handling<'a,E>>;

The thing is, in my code, I do this :

let handlers : Handlers = vec![
  Handling {
  handler : Box::from(|my_arg| { cast_function::<TypeA>(my_arg); ...}
},
  Handling {
  handler : Box::from(|my_arg| { cast_function::<TypeB>(my_arg); ...}
},
  Handling {
  handler : Box::from(|my_arg| { cast_function::<TypeC>(my_arg); ...}
},
]

I would LOVE to refactor this, in order to inject TypeA / TypeB / TypeC instead of my_arg into my closure parameter !

But is it possible ??? It would require to mix different generics in the same Vector, and I really don't know how to tackle the problem.

Note: I oversimplified the code in order to showcase my problem, I know my example doesn't compile, but my code do !

[tender dome]

you mean, you want each function to take TypeA (etc.) instead of the single type Arg?

you can do this, but what you have to do is wrap the function in a struct, make that struct implement a trait, and make a Vec<Box<dyn ThatTrait>>

and the implementation has to deal with however you get a TypeA to call the function, of course

the key is that all of the parts of the code that contain a specific type must be inside, not outside of the trait