Type System

Type System Architecture

The Entropy Type System provides static reflection and runtime introspection for C++ classes. It creates a bridge between static C++ types and dynamic systems like Scripting and Serialization.

Reflection Pipeline

The system uses a macro-based approach to register types at compile-time. These macros expand into static registration structures that populate the TypeRegistry at startup.

flowchart TD
    Source["C++ Class (UserProfile)"] --> Macros["Macros (ENTROPY_REGISTER_TYPE)"]
    Macros -->|Compile Time| Metadata["Static Metadata Structs"]
    Metadata -->|Static Init| Registry["Global TypeRegistry"]
    Registry -->|Runtime| Usage["Serialization / Scripting"]

    subgraph Macro Expansion
    Macros -- Generates --> TypeInfo["TypeInfo::create<T>()"]
    Macros -- Generates --> FieldList["std::vector<FieldInfo>"]
    end

Core Components

TypeInfo

Stores metadata for a single type.

• Name: String identifier (via getStaticTypeName).
• TypeID: Unique 64-bit hash.
• Fields: List of member variables (FieldInfo).
• Size/Alignment: Memory layout details.

FieldInfo

Metadata for a single member variable.

• Name: “creditBalance”.
• Offset: Byte offset from this (via offsetof).
• TypeID: ID of the field’s type.
• IsExtension: Flag for USD schema extensions (via ENTROPY_FIELD_EXTENSION).

Serialization Workflow

The primary use case for the type system is zero-boilerplate serialization.

1. Traverse: The Serializer iterates over TypeInfo::getFields().
2. Access: Uses offset to read data from the instance pointer.
3. Write: Dispatches to the appropriate writer based on the field’s TypeID.