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How to find the type of the caller of a function in Rust?

How can I get the caller type in my function?

struct A;
struct B;

impl A {
fn new() -> Self {
A
}
fn call_function(&self) {
B::my_function();
}
}

impl B {
pub fn my_function() {
println!("Hello");
// println!("{}" type_of_the_caller) // I want to get type A here
// Is it possible to get the caller type which is A in this case?
}
}

fn main() {
let a = A::new();
a.call_function();
}


Here is the working code in playground. This is simplified code for an example.

fn call_function(&self)

Suscriber

1 Answer
1

Rust doesn't have any machinery like this built-in. If you want to know some context inside a function then you'll need to pass it in as an argument.

Also, Rust doesn't have a way to get the name of a type, so you'd have to provide that too. For example, using a trait:

trait Named {
fn name() -> &'static str;
}

impl Named for A {
fn name() -> &'static str {
"A"
}
}


Which you might use like this:

impl B {
pub fn my_function<T: Named>(_: &T) {
println!("Hello");
println!("{}", T::name());
}
}


You have to pass in the caller when you call it:

impl A {
fn call_function(&self) {
B::my_function(self);
}
}


Outputs:

Hello
A


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