In this short tutorial I'll show how to run Lua programs from C and C and how to expose functions to them. Update: The code in this post has been updated for Lua 5.2.4. I haven't checked if the Lua 5.3 C API is backwards-compatible with 5.2. All the code here is available on GitHub. This project is useful in any environment where Lua code is accepted, with the powerful option of simply declaring any existing API using TypeScript declaration files. Type Safety Static types can ease the mental burden of writing programs, by automatically tracking information the programmer would otherwise have to track mentally in some fashion. Create a Lua state — like a Lua virtual machine in which our script will be running. Load the needed Lua libraries to run the script. Run the Lua script. Close the Lua state. The project must link to the Lua libraries, that have been compiled previously, and must have access to the Lua header directory, since we will be including the lua.hpp.

LuaJIT adds some extensions to the standard Lua/C API. The LuaJIT includedirectory must be in the compiler search path (-Ipath)to be able to include the required header for C code:

Or for C++ code:

`luaJIT_setmode(L, idx, mode)`— Control VM

This is a C API extension to allow control of the VM from C code. Thefull prototype of LuaJIT_setmode is:

The returned status is either success (1) or failure (0).The second argument is either 0 or a stack index (similar to theother Lua/C API functions).

The third argument specifies the mode, which is 'or'ed with a flag.The flag can be LUAJIT_MODE_OFF to turn a feature off,LUAJIT_MODE_ON to turn a feature on, orLUAJIT_MODE_FLUSH to flush cached code.

The following modes are defined: https://viewerever.amebaownd.com/posts/18931117.

Lua Script Copy

`luaJIT_setmode(L, 0, LUAJIT_MODE_ENGINE|flag)`

Turn the whole JIT compiler on or off or flush the whole cache of compiled code.

`luaJIT_setmode(L, idx, LUAJIT_MODE_FUNC|flag)`
`luaJIT_setmode(L, idx, LUAJIT_MODE_ALLFUNC|flag)`
`luaJIT_setmode(L, idx, LUAJIT_MODE_ALLSUBFUNC|flag)`

This sets the mode for the function at the stack index idx orthe parent of the calling function (idx = 0). It eitherenables JIT compilation for a function, disables it and flushes anyalready compiled code or only flushes already compiled code. Thisapplies recursively to all sub-functions of the function withLUAJIT_MODE_ALLFUNC or only to the sub-functions withLUAJIT_MODE_ALLSUBFUNC.

`luaJIT_setmode(L, trace, LUAJIT_MODE_TRACE|LUAJIT_MODE_FLUSH)`

Lua Script Checker

Flushes the specified root trace and all of its side traces from the cache.The code for the trace will be retained as long as there are any othertraces which link to it.

`luaJIT_setmode(L, idx, LUAJIT_MODE_WRAPCFUNC|flag)`

This mode defines a wrapper function for calls to C functions. Ifcalled with LUAJIT_MODE_ON, the stack index at idxmust be a lightuserdata object holding a pointer to the wrapperfunction. From now on all C functions are called through the wrapperfunction. If called with LUAJIT_MODE_OFF this mode is turnedoff and all C functions are directly called.

Lua Script Cheat Table

The wrapper function can be used for debugging purposes or to catchand convert foreign exceptions. But please read the section onC++ exception interoperabilityfirst. Recommended usage can be seen in this C++ code excerpt:

Note that you can only define a single global wrapper function,so be careful when using this mechanism from multiple C++ modules.Also note that this mechanism is not without overhead.

luaJIT_setmode(L, idx, mode)— Control VM

Lua Script Copy

luaJIT_setmode(L, 0, LUAJIT_MODE_ENGINE|flag)

luaJIT_setmode(L, idx, LUAJIT_MODE_FUNC|flag)luaJIT_setmode(L, idx, LUAJIT_MODE_ALLFUNC|flag)luaJIT_setmode(L, idx, LUAJIT_MODE_ALLSUBFUNC|flag)

luaJIT_setmode(L, trace, LUAJIT_MODE_TRACE|LUAJIT_MODE_FLUSH)