Re: lua_setfield vs lua_rawset

[Rici Lake <lua@...>]

On 19-Oct-05, at 12:00 PM, Chris Marrin wrote:

> But the decision was made to provide the particular variant of 
> lua_setfield(), which is extremely useful. And since the "raw" 
> variants add a useful (and sometimes critical) optimization of their 
> own, it seems that the equivalent lua_rawsetfield() would have been a 
> good choice.

Have you actually benchmarked the difference in performance between 
lua_settable() and lua_rawset()? It seems to me to be hardly noticeable 
in the normal case. (That's not the same situation as lua_rawseti().)

Using lua_rawset() instead of lua_settable() produces surprising 
results (surprising to the client of the library, that is) because it 
doesn't respect metatables. There is no difference when the table has 
no metatable, or when the key already exists.

I would strongly discourage use of rawset except in cases where it is 
actually necessary because you have to bypass the __newindex 
metamethod. Such cases are quite rare (usually confined to 
implementation of __newindex itself).