0_idea.md

I'd like to set an upvalue for a lua block from the c-api.

The idea is that I will load a lua file via c, and set an upvalue so the lua block that's executed knows it was loaded from the c-layer. Any subsequent loads that that block makes, should not see that same upvalue, so that code knows it was loaded indirectly from another lua script.

1_upval.c

status = luaL_loadfile ( state, "2_upvalfromc.lua" )

// Can I set an upvalue for the block compiled by luaL_loadfile, such that I can check the value in the block?

lua_call ( state, 0, 0 );

2_upvalfromc.lua

if (up_val_from_c) {
  -- I want to define this upvalue in c
  print ("upvalue came from c: " .. up_val_from_c)
else {
  print ("OOPS: up_val_from_c not defined")
}

dofile('3_not_from_c.lua')

3_not_from_c.lua

if (up_val_from_c) {
  -- Unexpected. I don't want this upvalue to be defined.
  print ("OOPS: upvalue came from c: " .. up_val_from_c)
} else {
  -- I expect this to not have the upvalue defined and print this statement.
  print ("Yes. This was loaded from within lua, not c")
}