simonask/reflect

A simple C++11 reflection/serialization framework.

C++ reflection and serialization framework

This is a simple library that allows for simple reflection and serialization of C++ types. It is designed for use in video game engines, or other rich environments in which runtime object creation and reflection is useful.

Features

• No meta-object compiler / preprocessing build step.
• Composite types ("aspect oriented programming") with rich interface casts.
• Simple serialization (to JSON at the moment).
• Simple and efficient signal/slot implementation included.
• Type-safe.
• C++11 compliant and extensible -- for instance, serializers for custom types can be easily defined, without modification to those types.

Planned/pending features

• YAML serialization.
• XML serialization.
• Built-in support for serialization of more standard library types.

Limitations

• Objects must derive from the Object type and include the REFLECT tag in their definition.
• Requires runtime type information.
• Members of objects that aren't described by a property(member, name, description) will not be serialized/deserialized.
• Class reflection/serialization with properties does not currently support multiple inheritance with non-interface (non-abstract) base classes. Use composite objects if needed. A class can derived from multiple base classes, but only one of them may derive from Object.

Examples

In foo.hpp:

#include "object.hpp"

class Foo : public Object {
    REFLECT;
public:
    Foo() : an_integer_property(123) {}
    void add_number(float32 n) { a_list_of_floats.push_back(n); }
    void say_hi() { std::cout << "Hi!\n"; }
private:
    int32                an_integer_property;
    Array<float32> a_list_of_floats;
};

In foo.cpp:

#include "foo.hpp"
#include "reflect.hpp"

BEGIN_TYPE_INFO(Foo)
    property(&Foo::an_integer_property, "Number",     "An integer property.");
    property(&Foo::a_list_of_floats,    "Float list", "A list of floats.");

    slot(&Foo::say_hi, "Say Hi!", "A slot that says hi.");
END_TYPE_INFO()

In main.cpp:

int f() {
      // Create a universe for our objects to live in.
      TestUniverse universe;

    // Print the type name and all properties.
    auto foo_type = get_type<Foo>();
    std::cout << foo_type->name() << '\n'; // prints "Foo"
    for (auto attribute: foo_type->attribute()) {
        std::cout << attribute->name() << ": " << attribute->type()->name() << '\n';
    }
    std::cout << '\n';

    // Create a composite type consisting of two Foos.
    CompositeType* composite = new CompositeType("FooFoo");
    composite->add_aspect(get_type<Foo>());
    composite->add_aspect(get_type<Foo>());
    Object* c = universe.create_object(composite, "My object");
    Foo* f = aspect_cast<Foo>(c); // get a pointer to the first Foo in c.
    f->add_number(7);
    f->say_hi();
    
    // Serialize the composite as JSON, and write to stdout.
    JSONArchive archive;
    archive.serialize(c, universe);
    archive.write(std::cout);
}

Output:

Foo
Number: int32
Float list: float32[]

{ "root": {
      "id": "My object",
      "aspects": [
        {
	        "class": "Foo",
	        "Float list": [7],
	        "Number": 123
        },
        {
          "class": "Foo",
          "Float list": null,
          "Number": 123
        }
      ],
      "class": "FooFoo"
    }
}