Help on declarative macro

help
1

Help on declarative macro.
I want a macro that takes other macros as input and inside the main macro, expands the other macros and grab their input and use their inputs.
How do I do that
e.g

macro_rules! example {
    (???) => {
        ???
        // use the expanded information and pass it on
    }
}
2

It is not possible for a declarative macro to see the output of another macro.

Even if you could, you usually shouldn’t, because the exact expansion of a macro is often an implementation detail subject to change.

3

I just clarifying so this is not possible

macro_rules! custom {
    (???) => {
        ???
        custom!(???);
        // The ??? Is I don’t know what to put, not literal tokens input
    }
    ($lit:literal) => {
         // Do whatever
    }
}
fn main() {
    custom!(format!(“{}”, “aa”));
    custom!(some_another_macro!());
}
4

You could match the tokens of the format!() macro call itself, but you can't expand it.