The Hierarchy of an Object + Class

object.cairo

from starkware.cairo.common.alloc import alloc
from starkware.cairo.common.invoke import invoke
from starkware.cairo.common.registers import get_ap, get_label_location

struct Class:
    member _ : felt*
    member name : felt
    member super : Class*
    member size : felt
    member ctor : codeoffset  # constructor
    member differ : codeoffset
    member puto : codeoffset
end

struct Object:
    member class : Class*
end

const CLASS_NAME =  427020088179     # str_to_felt('Class')
const OBJECT_NAME = 122468482507636  # str_to_felt('Object')

namespace _Class:
    func compare(self : Class, b : Class) -> (f : felt):
        if self.name == b.name:
            return (0)
        else:
            return (1)
        end
    end

    func display():
        %{ print('Class:') %}
        return ()
    end

    func class__() -> (class_ : Class*):
        alloc_locals
        let (class_ : Class*) = alloc()
        let (obj_instance) = _Object.class__()
        assert class_[0] = Class(
            _=cast(class_, felt*),
            name=CLASS_NAME,
            super=obj_instance,
            size=Class.SIZE,
            ctor=make_class,
            differ=compare,
            puto=display,
            )
        return (class_=class_)
    end

    func make_class():
        let (class_) = class__()
        let obj = Object(class=class_)
        return ()
    end
end

namespace _Object:
    func make_object(class_ : Class*) -> (obj : Object):
        let obj = Object(class=class_)
        return (obj)
    end

    func compare(self : Object, b : Object) -> (f : felt):
        if self.class.name == b.class.name:
            return(0)
        else:
            return (1)
        end
    end

    func display():
        %{ print('Object:') %}
        return ()
    end

    func class__() -> (class : Class*):
        let (class_ : Class*) = alloc()
        assert class_[0] = Class(
            _=class_,
            name=OBJECT_NAME,
            super=class_,
            size=Object.SIZE,
            ctor=make_object,
            differ=compare,
            puto=display,
            )
        return (class=class_)
    end
end

func main():
    let (cls) = _Class.class__()
    let c : Class = cls[0]
    let d : Class* = cast(c._, Class*)
    let e : Class* = cast(d._, Class*)
    let f : Class* = cast(e._, Class*)
    let g : Object* = cast(f[0].super, Object*)

    return ()
end