How to generate plantuml class diagrams from c++ code using hpp2plantuml

Introduction

Accurate documentation is vital to any software project. However, this process can be time consuming and is often overlooked specially in projects with a tight schedule and budget. Generating documentation like UML diagrams from source code can definitely save a lot of time.

We would like to show you a way to do this for C++ projects by using hpp2plantuml https://hpp2plantuml.readthedocs.io/en/latest/index.html

Installation

sudo apt install plantuml
pip3 install hpp2plantuml

Structure

Consider the following files

IAnimal.hpp

#ifndef IANIMAL_HPP
#define IANIMAL_HPP

class IAnimal {
public:
    virtual ~IAnimal() {}
    virtual void makeSound() = 0;
};

#endif

Cat.hpp

#ifndef CAT_HPP
#define CAT_HPP

#include "IAnimal.hpp"
#include <iostream>

class Cat : public IAnimal {
public:
    void makeSound() override {
        std::cout << "Meow!" << std::endl;
    }
};

#endif

Dog.hpp

#ifndef DOG_HPP
#define DOG_HPP

#include "IAnimal.hpp"
#include <iostream>

class Dog : public IAnimal {
public:
    void makeSound() override {
        std::cout << "Woof!" << std::endl;
    }
};

#endif

AnimalShelter.hpp

#ifndef ANIMAL_SHELTER_HPP
#define ANIMAL_SHELTER_HPP

#include "IAnimal.hpp"
#include <vector>
#include <memory>

class AnimalShelter {
private:
    std::vector<std::shared_ptr<IAnimal>> animals;
public:
    void addAnimal(std::shared_ptr<IAnimal> animal) {
        animals.push_back(animal);
    }

    void makeAllSounds() {
        for (const auto& animal : animals) {
            animal->makeSound();
        }
    }
};

#endif

Generate diagram

Using the following command you can generate the UML class diagram

hpp2plantuml -i "*.hpp" -o out.puml

To create an svg image do

plantuml -tpng out.puml

This will produce the diagram like the following

If you want to produce an svg pass the -tsvg flag to the plantuml binary

The program is also able to identify namespaces and render them as modules for example:

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