majiayu000 Observer Pattern (Callbacks)
Objects register interest in events and get notified when they occur. In C, implemented as callback function pointers with context.
ikigai Application
Streaming chunks: LLM client notifies REPL as response chunks arrive:
typedef void (*chunk_callback_t)(void *ctx, const char *chunk, size_t len);
res_t ik_llm_stream(client, messages, on_chunk, user_ctx);
Terminal resize: Signal handler notifies REPL of SIGWINCH.
Future uses:
- Database change notifications
- Tool execution progress
- Background task completion
Convention: Always pair callback function pointer with void *user_ctx parameter.