Entt: Request for Adding Polypropylene to Similar Projects List in Wiki

[pmbittner]

Dear Michele Caini,

May I ask you to add my ECS Polypropylene to your Similar-Projects List in your wiki?

Polypropylene stands for _POLYmorphism aware PROPertY Library for mutablE dyNamic objEcts_ (😅) and is a prototypical C++17 library. It is a hybrid solution between an ECS and dynamic mixins with a focus on supporting polymorphism and multiplicity on components. To this end, Polypropylene is more object-oriented and not a strict ECS. If I saw correctly, the biggest design differences to EnTT are that:

• an entity in Polypropylene may have multiple components of the same type if desired,
• a component in Polypropylene can be obtained from an entity by any of its polymorphic types.

which Polypropylene pays for with a more intrusive API (and very likely worse performance) than EnTT (Note, in Polypropylene components are called Properties):

class Pizza : public PAX::Entity<Pizza> {};

class TomatoSauce : public PAX::Property<Pizza> {
    PAX_PROPERTY(TomatoSauce, PAX_PROPERTY_IS_CONCRETE)
    PAX_PROPERTY_DERIVES(PAX::Property<Pizza>)
    PAX_PROPERTY_IS_SINGLE

public:
    unsigned int scoville = 0;
};

class Cheese : public PAX::Property<Pizza> {
    PAX_PROPERTY(Cheese, PAX_PROPERTY_IS_ABSTRACT)
    PAX_PROPERTY_DERIVES(PAX::Property<Pizza>)
    PAX_PROPERTY_IS_MULTIPLE

    PAX_PROPERTY_DEPENDS_ON(TomatoSauce)
};

class Mozzarella : public Cheese {
    PAX_PROPERTY(Mozzarella, PAX_PROPERTY_IS_CONCRETE)
    PAX_PROPERTY_DERIVES(Cheese)
    PAX_PROPERTY_IS_SINGLE
};


Pizza pizza;
pizza.add(new TomatoSauce()); // otherwise we cannot add cheese
pizza.add(new Mozzarella());

// no dynamic_casts here
pizza.get<TomatoSauce>()->scoville = 3000; // put Tabasco in ;)
Mozzarella * mozzarella = pizza.get<Mozzarella>();
const std::vector<Cheese*>& cheeses = pizza.get<Cheese>(); // There might be multiple cheese types apart from mozzarella, so we get a vector.

There are more features in Polypropylene but this should be a more than detailed introduction to my work. 😊

Thanks in any case and kind regards 🍕
Paul

[skypjack]

Yeah, sure. I'd be glad to add it. 🙂
Do you want to create a PR for it, so that you can customize the description?
Otherwise I can add it on my own. Not a problem. Just le me know. Thanks.

[skypjack]

Done.

[pmbittner]

Wow, cool thank you very much! :) The description is great!
Sorry, that I couldn't respond earlier.
I also didn't know yet that pull-requests also work on changes to a project's wiki, so lesson learned for next time. :)

Cheers
Paul

[skypjack]

didn't know yet that pull-requests also work on changes to a project's wiki

They don't afaik. 🙂
It's just that the wiki pages are also in the repo for EnTT, because they are used to generate part of the online documentation.

[pmbittner]

Oh cool! Storing all the documentation in the repository itself sounds like a good idea in general. I will have a look at how you do it. :) I already wondered why this is not the default for GitHub wikis as Github already adds a .github directory to the repository for other GitHub related tasks. 🤷‍♂️

[skypjack]

Maybe it is and I'm not aware of it. If you discover something, PLEASE inform me. 😄

[pmbittner]

You, too. :D So for now, you copy the contents of your files in docs/md/ by hand each time after a change?

[skypjack]

Yeah, exactly. I update them for the autogenerated online documentation, so I would do it anyway, then I copy the same files to the wiki when needed. 🤷‍♂️