CODESAMPLE

Builder - Rust

Builder Rust

The Builder pattern allows for the construction of complex objects step-by-step. It separates the object construction logic from its representation, enabling the creation of different variations of the object without altering the core construction process. This is achieved through a builder struct that holds the object’s attributes and provides methods to set them. A final build() method then assembles the object.

The Rust implementation uses a struct for the builder, holding the fields of the target object. Methods on the builder return self to enable chaining. The build() method consumes the builder and returns the constructed object. This approach leverages Rust’s ownership and move semantics for safety and efficiency, and the fluent interface created by chaining methods is a common Rust idiom for configuration.

// Target object
#[derive(Debug)]
struct Computer {
    cpu: String,
    ram: u32,
    storage: String,
    has_gpu: bool,
}

// Builder struct
struct ComputerBuilder {
    cpu: String,
    ram: u32,
    storage: String,
    has_gpu: bool,
}

impl ComputerBuilder {
    fn new() -> Self {
        ComputerBuilder {
            cpu: String::from("Intel i5"),
            ram: 8,
            storage: String::from("HDD"),
            has_gpu: false,
        }
    }

    fn cpu(mut self, cpu: String) -> Self {
        self.cpu = cpu;
        self
    }

    fn ram(mut self, ram: u32) -> Self {
        self.ram = ram;
        self
    }

    fn storage(mut self, storage: String) -> Self {
        self.storage = storage;
        self
    }

    fn has_gpu(mut self, has_gpu: bool) -> Self {
        self.has_gpu = has_gpu;
        self
    }

    fn build(self) -> Computer {
        Computer {
            cpu: self.cpu,
            ram: self.ram,
            storage: self.storage,
            has_gpu: self.has_gpu,
        }
    }
}

fn main() {
    let gaming_pc = ComputerBuilder::new()
        .cpu(String::from("Intel i9"))
        .ram(32)
        .storage(String::from("SSD"))
        .has_gpu(true)
        .build();

    let office_pc = ComputerBuilder::new()
        .ram(16)
        .storage(String::from("SSD"))
        .build();

    println!("Gaming PC: {:?}", gaming_pc);
    println!("Office PC: {:?}", office_pc);
}