CODEWITHSUNDEEP
crustwarningsunused-variables
Jaysmito Mukherjee
Jaysmito Mukherjee

Reputation: 1526

(void)variable alternative for Rust

As the title says is there an alternative for (void)variable like C/C++ in Rust.

I have a callback function which look something like:

fn on_window_event(window: &cgl_rs::Window, event: &cgl_rs::Event) -> bool {
    // ... some code ...
    false
}

Here I do not use the window variable, so I get the unused warning.

I know that I can disable the warning but I wanted to know whether we can deal with this in any other nice way.

Upvotes: 2

Views: 336

Answers (1)

Finomnis
Finomnis

Reputation: 22808

In Rust, an underscore (_) at the beginning of the name is used to mark variables as unused.

pub fn foo(a: i32, b: i32) -> i32 {
    b * 2
}

$ cargo check
warning: unused variable: `a`
 --> src\lib.rs:1:12
  |
1 | pub fn foo(a: i32, b: i32) -> i32 {
  |            ^ help: if this is intentional, prefix it with an underscore: `_a`
  |
  = note: `#[warn(unused_variables)]` on by default

pub fn foo(_a: i32, b: i32) -> i32 {
    b * 2
}

$ cargo check
- no warning -

Upvotes: 4

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