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On 19/08/2016 01:48, ThePhD wrote:
Well, I looked into this deeper after everyone gave me the conventional wisdom to NOT depend on `lua_next`'s iteration order and pray for no breaking changes.

It turns out that the correct wisdom -- iterate using an index value -- seems to also be the most performant wisdom from the C++ or C side. [1] compares the performance of calling `lua_next()` in a while loop and assuming it iterates in the right order, pushing a table and calling `lua_geti` with the indices (and knowing the size and indices before hand), and the other measures the doing a lua_pushinteger + lua_gettable. Measured in a computer with an i7 Intel chip, lots of ram, Windows 10, Lua 5.3.3 compiled as a DLL.

Interestingly, the pushinteger + gettable method is about equal to the lua_next implementation. So, for Lua 5.2 and lower, since there's no lua_geti intrinsically built into the API, the correct way is equal in performance to the UB way.

There is however a lua_rawgeti method that you can use.