The purpose of LUA_ENVIRONINDEX pseudo index

[Jose Luis Hidalgo Valiño <joseluis.hidalgo@...>]

Hi All! ,
I'm not sure to completely understand the purpose of the  
LUA_ENVIRONINDEX pseudo index. This is new to lua 5.1 and is the  
pseudo index to access the environment of the running C function. Ok,  
is this the global table of the running C function ? is by default  
the same as the LUA_GLOBALSINDEX if not changed by a lua_setfenv ?  
Should we use it by default instead of LUA_GLOBALSINDEX (it is more  
correct to try access the current environment)? is LUA_GLOBALSINDEX a  
way to always access the thread environment ignoring a lua_setfenv ?

Can anybody give an example where the lua_environment is useful, or  
an example where lua_globalsindex can not be used? For example, could  
lua_environindex be used to hold data locally( or private ) to a C  
function that can be accessed in successive calls?

Thank you!

   PpluX