> Tagged unions would be, except they aren't first class in C.
For the originally stated example, 'declare a variable, set it to 5 (number), and then set it to the "hello" (string)', a plain union is just fine.
> The best analogy here would probably be OCaml polymorphic variants
It would be, except OCaml is not C.
> It is not, though, because - unlike JavaScript - the fact that everything is a reference to object
Evidently, references and pointers are not the same thing, hence it is an implementation detail whether references correspond to pointers.
> and each object has a unique identity
Which doesn't necessarily have anything to do with their address. It's an opaque value guaranteed to be unique for an object for the duration of its lifetime.
Meanwhile, C pointer values aren't necessarily unique for different objects. For example, a pointer to a struct with one or more fields shares value with a pointer to its first field. It's only once you factor in type that pointers uniquely identify a particular object, so they don't exactly correspond to Python's object identity.
For the originally stated example, 'declare a variable, set it to 5 (number), and then set it to the "hello" (string)', a plain union is just fine.
> The best analogy here would probably be OCaml polymorphic variants
It would be, except OCaml is not C.
> It is not, though, because - unlike JavaScript - the fact that everything is a reference to object
Evidently, references and pointers are not the same thing, hence it is an implementation detail whether references correspond to pointers.
> and each object has a unique identity
Which doesn't necessarily have anything to do with their address. It's an opaque value guaranteed to be unique for an object for the duration of its lifetime.
Meanwhile, C pointer values aren't necessarily unique for different objects. For example, a pointer to a struct with one or more fields shares value with a pointer to its first field. It's only once you factor in type that pointers uniquely identify a particular object, so they don't exactly correspond to Python's object identity.