ezEngine Release 26.3
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ezGenericId< InstanceIndexBits, GenerationBits > Struct Template Reference

Generic identifier template that combines instance indexing with generation counting for safe object references. More...

#include <Id.h>

Public Types

enum  { STORAGE_SIZE = ((InstanceIndexBits + GenerationBits - 1) / 8) + 1 }
 
using StorageType = typename ezSizeToType< STORAGE_SIZE >::Type
 

Public Member Functions

 EZ_DECLARE_ID_TYPE (ezGenericId, InstanceIndexBits, GenerationBits)
 
EZ_ALWAYS_INLINE ezGenericId (StorageType instanceIndex, StorageType generation)
 

Public Attributes

union { 
 
   StorageType   m_Data 
 
   struct { 
 
      StorageType   m_InstanceIndex: InstanceIndexBits 
 
      StorageType   m_Generation: GenerationBits 
 
   }  
 
};  
 

Detailed Description

template<ezUInt32 InstanceIndexBits, ezUInt32 GenerationBits>
struct ezGenericId< InstanceIndexBits, GenerationBits >

Generic identifier template that combines instance indexing with generation counting for safe object references.

This ID system solves the "dangling pointer" problem for object management by using a two-part identifier:

  • Instance Index: Points to a slot in an object array or similar data structure
  • Generation Counter: Detects when a slot has been reused for a different object

When an object is destroyed, its generation counter is incremented. Any existing IDs with the old generation value become automatically invalid, preventing access to the new object that might occupy the same index.

Benefits:

  • Safe object references that can detect stale access
  • Efficient array-based object storage with O(1) access
  • Automatic detection of use-after-free scenarios
  • Compact representation (configurable bit allocation)
  • Type safety when used with EZ_DECLARE_HANDLE_TYPE

Template parameters allow customization of the index space vs. generation granularity:

  • More instance bits = larger object arrays possible
  • More generation bits = longer time before wraparound reuse

Typical configurations:

  • ezGenericId<24, 8>: 16M objects, 256 generations (good for most uses)
  • ezGenericId<16, 16>: 64K objects, 65K generations (for high-churn scenarios)
The documentation for this struct was generated from the following file: