Data is code and code is data. There's really no difference.
A few reasons why in C++, C, and Lua, and in general in most game programming languages code is not the same as data:
- Tends not to be editor friendly
- Requires heavy meta programming to achieve the same as other formats
- Requires compilation and/or interpretation
- Is not necessarily idempotent depending on compiler options and platform. The same data should be the same cross-platform, and code is almost definitely not because at a minimum level, it can generate vastly different assembly depending on compiler flags or processor targets.
- Purely composite. I would argue that as much as we try, it's hard to compose a lot of code properly and without considerable effort in games. Conversely, composing data can be quite easy.
- Cannot on its own be serialized/deserialized easy while in a runtime state
- Not network transparent
- Cannot be compressed/decompressed in real-time as easily
See my points in other posts in this thread. I am assuming you downvoted me, which is ridiculous and childish, especially given your brief response without any reasoning or evidence despite being contrary to all computer science research.
Composition: see meta-tables. Repeat until completion.
It's telling that all the major game engines and a large portion of papers and talks disagree with you. If Lua was the solution to data-driven development, people wouldn't bend over backwards looking for solutions like entity component systems. Lua is nice, but not suitable for most professional game development as a primary language. As such, it makes it completely unsuitable because Lua data, especially things that depend on runtime state are utterly useless.
Your shipping comment also makes no sense in this context. Tons of other languages have more games shipped than Lua. There aren't too many people relying on Lua for composition and data-driven development in games, because it doesn't work. Even Lisp doesn't work in this context putting speed and other things aside, because of so many reasons I've already listed. Code in the context of game development is not data by the definition of data I am referencing.