C++ equivalent of algebraic datatype?

Question

Let\'s say I have this Haskell code:

data RigidBody = RigidBody Vector3 Vector3 Float Shape -- position, velocity, mass an         


        

Answer 1

To throw another possibility in here, you can also use boost::variant which is being added to the standard library in C++17 as std::variant:

struct Ball { float radius; };
struct ConvexPolygon { Triangle t; }

using Shape = boost::variant;

The advantages of this approach:

• Type-safe, unlike tagged unions
• Can hold complex types, unlike unions
• Does not require a uniform interface across all "child" types, unlike OO

Some disadvantages:

• Sometimes requires you to do a type check when accessing the variable to confirm that it is the type you want it to be, unlike OO
• Requires you to use boost, or be C++17 compatible; these may be difficult with some compilers or some organizations where OO and unions are universally supported