Versioned internal references

[bedeho]

Currently, it is not possible to require that reference to some entity in a class has to support some specific schema versions. It makes sense to allow expressing this more harsh constraint, and it will be a requirement when wanting to introduce certain new types of schema upgrades.

A simple way could be to change Internal(ClassId) to Internal(ClassId, Option<VersionConstraint>) in PropertyType, where VersionConstraint can be something like

enum VersionConstraint {
Exactly(u16),
AtLeast(u16)
}

[siman]

What about more flexible guards?

enum SchemaVersionConstraint {
  Gt(u16),
  Ge(u16),
  Eq(u16),
  Le(u16),
  Lt(u16),
}

// ... in PropertyType struct:
// where the first constraint is for lower bound
// and the second constraint is for upper bound:
Internal(ClassId, Option<SchemaVersionConstraint>, Option<SchemaVersionConstraint>)

Or more verbose version:

enum SchemaVersionConstraint {
  GreaterThanOrEqual(u16),
  GreaterThan(u16),
  Equal(u16),
  LessThan(u16),
  LessThanOrEqual(u16),
}

[bedeho]

I am not sure if it makes sense to have upper bounds? Is there a use case?