Hashing in Lua

[Martin_Doering@...]

Hi!

Today I came back from my holidays. There is one thing, which is not 
really clear to me:

I'm a C programmer for some years now. In C I can use structs and then 
access single "values" of the struct. I do this by pointers. The compiler 
calculates the address, where the actual value is written later at 
runtime.

How is such thing done in Lua? As far as I read in Lua everything except a 
single variable is stored in a table and accessed by name via a hash 
function. Is this right? Is this done at "compile to bytecode time" or is 
this a mechanism of the virtual machine? I think the last. If so, isn't it 
unfair to compare a language where I just work with adresses in memory to 
one with a more dbms-like structure? 

How are single values accessed? Is it right like this:

b = 5

The VM gets a reference to an adress, where the type of the object 
(variable - here a number) is stored. In dependence of this type an 
operation is beeing performed. The object b is set to number of 5. So 
somewhere in memory a (C-)double of 5 is stored in the end.

I ask this because of thinking on how to write programs in Lua to use 
efficient access mechanisms to data. For example: Use more struct like 
constructs or use more single global (or not) variables.

This all has, as I think, nothing to do with interpretation or 
compilation. It would work the same way in C, if I would use Lua just as 
an programming library and use it's data access mechanism.

Martin