CODESAMPLE

Module - Rust

Module Rust

The Module pattern organizes code into logical units, enhancing reusability, maintainability, and preventing naming conflicts. In Rust, modules are defined using the mod keyword. This example demonstrates a simple module structure with a public function and a private one. The pub keyword controls visibility, making items accessible outside the module. Rust’s module system is central to its package management (crates) and encourages a hierarchical organization of code. The use of mod and pub aligns with Rust’s explicit visibility control and emphasis on code organization.

// src/lib.rs

pub mod geometry {
    // Publicly available types and functions
    pub struct Rectangle {
        pub width: u32,
        pub height: u32,
    }

    impl Rectangle {
        pub fn area(&self) -> u32 {
            self.width * self.height
        }

        // Private function - only accessible within the geometry module
        fn is_square(&self) -> bool {
            self.width == self.height
        }

        pub fn new(width: u32, height: u32) -> Rectangle {
            Rectangle { width, height }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::geometry::Rectangle;

    #[test]
    fn test_rectangle_area() {
        let rect = Rectangle::new(5, 10);
        assert_eq!(rect.area(), 50);
    }

    #[test]
    fn test_is_square_access() {
        let rect = Rectangle::new(5, 5);
        // This would cause a compile error because is_square is private
        // assert_eq!(rect.is_square(), true);
    }
}