There are a couple reasons I would use separate constructor/init():
- Lazy/Delayed initialization. This allows you to create the object quickly, fast user response, and delay a more lengthy initialization for later or background processing. This is also a part of one or more design patterns concerning reusable object pools to avoid expensive allocation.
- Not sure if this has a proper name, but perhaps when the object is created, the initialization information is unavailable or not understood by whoever is creating the object (for example, bulk generic object creation). Another section of code has the know-how to initialize it, but not create it.
- As a personal reason, the destructor should be able to undo everything the constructor did. If that involves using internal init/deinit(), no problem, so long as they are mirror images of each other.
