Re: C API - lua_next traversal of "array" table

["Liam Devine" <liamdevine@...>]

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.

--Regards,
Liam