rust / intermediate
Snippet
Struct Methods with Impl
impl blocks define methods on structs. &self borrows the struct immutably, &mut self borrows mutably, and no self creates an associated function (constructor). Self refers to the implementing type. New is a convention for constructors, and square demonstrates a static factory method pattern.
snippet.rs
rust
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struct Rectangle {width: u32,height: u32,}impl Rectangle {fn new(width: u32, height: u32) -> Self {Rectangle { width, height }}fn area(&self) -> u32 {self.width * self.height}fn scale(&mut self, factor: u32) {self.width *= factor;self.height *= factor;}fn square(size: u32) -> Self {Self { width: size, height: size }}}fn main() {let rect = Rectangle::new(10, 5);println!("Area: {}", rect.area()); // 50let sq = Rectangle::square(4);println!("Square area: {}", sq.area()); // 16let mut r = Rectangle::new(3, 3);r.scale(2);println!("Scaled: {}x{}", r.width, r.height); // 6x6}
Breakdown
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impl Rectangle { ... }
Implementation block attaching methods to Rectangle struct
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fn new(width: u32, height: u32) -> Self
Associated function (constructor) returns new Rectangle instance
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fn area(&self) -> u32
Method borrowing self immutably, read-only access
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fn scale(&mut self, factor: u32)
Method borrowing self mutably, allows field modification
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Self { width, height }
Self alias avoids repeating struct name in constructor