majiayu000 Vtable Pattern (C-Specific)
Struct of function pointers enabling polymorphism. Different implementations provide different function pointer sets. Callers invoke through vtable.
ikigai Application
LLM providers:
typedef struct {
res_t (*send)(void *impl, ...);
res_t (*stream)(void *impl, ...);
void (*cleanup)(void *impl);
} ik_provider_vtable_t;
typedef struct {
ik_provider_vtable_t *vt;
void *impl; // OpenAI ctx, Anthropic ctx, etc.
} ik_llm_client_t;
Layer system: Each layer type provides render/resize functions.
Benefits:
- Runtime polymorphism without inheritance
- Swap implementations transparently
- Mock implementations for testing
Convention: Vtable struct named *_vtable_t, instance holds vt pointer plus impl context.