What is the Builder design pattern in C++?

What is the Builder design pattern in C++?

The Builder design pattern is a creational pattern that allows for the step-by-step construction of complex objects. It separates the construction of a complex object from its representation, enabling the same construction process to create different representations.

Can you give me an example of how to implement it?

Sure! Here's a simple example:

class Product {
public:
    void addPart(const std::string& part) {
        parts.push_back(part);
    }
    void showParts() {
        for (const auto& part : parts) {
            std::cout << part << " ";
        }
        std::cout << std::endl;
    }
private:
    std::vector<std::string> parts;
};

class Builder {
public:
    virtual void buildPartA() = 0;
    virtual void buildPartB() = 0;
    virtual Product getResult() = 0;
};

class ConcreteBuilder : public Builder {
public:
    ConcreteBuilder() { product = Product(); }
    void buildPartA() override { product.addPart("PartA"); }
    void buildPartB() override { product.addPart("PartB"); }
    Product getResult() override { return product; }
private:
    Product product;
};

class Director {
public:
    void setBuilder(Builder* b) { builder = b; }
    void construct() {
        builder->buildPartA();
        builder->buildPartB();
    }
private:
    Builder* builder;
};

This code defines a Product, a Builder interface, a ConcreteBuilder, and a Director that orchestrates the building process.

What are the advantages of using the Builder pattern?

The Builder pattern provides several advantages:

1. Separation of Concerns: It separates the construction of a complex object from its representation.
2. Flexibility: You can create different representations of an object using the same construction process.
3. Readability: The code becomes more readable and maintainable, as the construction logic is encapsulated.