Uobject upackage internals


All unreal objects have unique path in the form of string:


If you split the path using dot as delimiter you will get:

  1. /Game/MyGame/MyAsset

  2. MyAsset

  3. ASubObjectOfMyAsset

  4. AnotherObject

Outer most object is awlays a UPackage

  • In this example, it's /Game/MyGame/MyAsset

Object flags: Tell us the state of the object

  • RF_Public => this object is visible outside of its package
  • Example of non-public object is a sub-object
  • Every object you can see in editor is Public
  • RF_Standalone => Doesn’t need to be referenced to not be garbage collected
  • If containing package gets unloaded, then it gets GC'ed
  • RF_Transactional => property changes are recorded and can be reverted

Class flags: tell about the object's UClass

  • CLASS_Abstract => Class can't be instantiated
  • CLASS_Native => Native class
  • CLASS_Constructed

All native classes get populated in /Script/[ModuleName]

Native classes do not get a PostLoad


  • Object is still abstract entity


  • Properties initialized, including any set from config inis
  • NOTE: Any properties set on default subobjects inside the constructor get stomped by the CDO's properties when the constructor exits
  • So this is good place to put "per instance" constructor initialization data
  • Ex: Initializing transient data that (e.g. CurrentOwner) that would be null on the CDO
  • Ready to interact with the world

Serialized Assets get PostLoad

  • PostLoad is where default properties that are changed in the editor get loaded into the object
  • The reset to default yellow arrow simply applies the property's value from the CDO back into the current objects' property