abstract type SpaceObject end struct Asteroid <: SpaceObject # Asteroid fields end struct Spaceship <: SpaceObject # Spaceship fields end collide_with(::Asteroid, ::Spaceship) = # Asteroid/Spaceship collision collide_with(::Spaceship, ::Asteroid) = # Spaceship/Asteroid collision collide_with(::Spaceship, ::Spaceship) = # Spaceship/Spaceship collision collide_with(::Asteroid, ::Asteroid) = # Asteroid/Asteroid collision collide(x::SpaceObject, y::SpaceObject) = collide_with(x, y)
collide function calls
collide_with which, at runtime, will inspect the
types of its arguments and dispatch to the appropriate implementation.
Julia was created with multiple dispatch as a first-class citizen, it is used liberally in its ecosystem. C++ does not have access to such a feature natively, but there are alternatives that I will be presenting in this article, and try to justify there uses and limitations.