Lua - Is there a different function in the Lua library that is identical or similar to debug.getupvalues / debug.getupvalue?

Question

Is it possible or is there a function that works similar to debug.getupvalues / debug.getupvalue in the lua library that I could use, as I won't be able to use either soon and I depend on them slightly to keep parts of the code I have working.

Also if I could get the function code for debug.getupvalue it would be a great help as I could just use that as a function instead of using the debug library anymore, although I doubt it is code in Lua.

And before you say it, yes I know the debug library is the most undependable library in all of Lua but it made my code work and I would like to find a way to stop using it before it's too late.

Answer 1

The debug library is not meant to be used in production code (as opposed to tests and unusual debugging situations). There are 3 possible solutions. Two of them require changes to the code where the closures are defined. The other would require you to know C:

1. Add more closures in the same scope as the upvalues that will give you the access that you need.

2. Use tables instead of closures.

3. Write a C library that makes use of lua_getupvalue.

To see the source code of debug.getupvalue, download Lua 5.3.5 and look at src/ldblib.c, line 260. lua_getupvalue is in src/lapi.c, line 1222.