# Global Singletons Declare a global singleton with `global Name { /* .. properties or callbacks .. */ }` to make properties and callbacks available throughout the entire project. Access them using `Name.property`. For example, this can be useful for a common color palette: ```slint,no-preview global Palette { in-out property primary: blue; in-out property secondary: green; } export component Example inherits Rectangle { background: Palette.primary; border-color: Palette.secondary; border-width: 2px; } ``` Export a global to make it accessible from other files (see [Modules](modules.md)). Export a global from the file also exporting the main application component to make it visible to native code in the business logic. ```slint,ignore export global Logic { in-out property the-value; pure callback magic-operation(int) -> int; } // ... ```

Usage from Rust

```rust slint::slint!{ export global Logic { in-out property the-value; pure callback magic-operation(int) -> int; } export component App inherits Window { // ... } } fn main() { let app = App::new(); app.global::().on_magic_operation(|value| { eprintln!("magic operation input: {}", value); value * 2 }); app.global::().set_the_value(42); // ... } ```

Usage from C++

```cpp #include "app.h" fn main() { auto app = App::create(); app->global().on_magic_operation([](int value) -> int { return value * 2; }); app->global().set_the_value(42); // ... } ```

Usage from JavaScript

```js let slint = require("slint-ui"); let file = slint.loadFile("app.slint"); let app = new file.App(); app.Logic.magic_operation = (value) => { return value * 2; }; app.Logic.the_value = 42; // ... ```

It's possible to re-expose a callback or properties from a global using the two way binding syntax. ```slint,no-preview global Logic { in-out property the-value; pure callback magic-operation(int) -> int; } component SomeComponent inherits Text { // use the global in any component text: "The magic value is:" + Logic.magic-operation(42); } export component MainWindow inherits Window { // re-expose the global properties such that the native code // can access or modify them in-out property the-value <=> Logic.the-value; pure callback magic-operation <=> Logic.magic-operation; SomeComponent {} } ```