Lua C Integration

Create a C extension by writing C functions, registering them with Lua's C API, and compiling them as a shared library. Use lua_pushcclosure to register functions and luaL_newlib to create a module table, then load it in Lua with require().

The Lua stack is a last-in-first-out buffer that exchanges values between Lua and C. Push values onto the stack with lua_push* functions, pop them with lua_pop, and access them by index. Stack positions are 1-indexed from the bottom; negative indices count from the top.

Yes. Push the Lua function onto the stack, push its arguments, then call lua_pcall or lua_call to execute it. lua_pcall handles errors safely by returning an error code instead of unwinding the stack.

Use Lua's allocator for objects shared with Lua to ensure consistent memory lifecycle. For C-only objects, use standard malloc/free. Implement __gc metamethods for userdata to clean up C resources when Lua garbage-collects them.

Create userdata with lua_newuserdata, assign a metatable with luaL_newmetatable to define behavior, and register __index, __newindex, and __gc metamethods. This lets Lua code treat C structs as first-class objects with methods and finalizers.

Embed Lua when C is your application core and you want to add scripting, configuration, or plugin support without building a separate layer. Embedding gives you control over Lua's initialization, lifetime, and resource constraints within a C host.