Re: Does funtion & variable name lengths effect speed?

[Rici Lake <lua@...>]

On 10-Oct-05, at 1:31 PM, Chris Marrin wrote:

> Adam D. Moss wrote:
> > Posti Laatikko wrote:
> > > Since lua is intepreted language i was wondering does variables & 
> > > funtions
> > > names effect execution speed if names are long?
> > Nope - they're just strings which are interned and then
> > compared/hashed by pointer.
>
> But technically a long string takes longer to do the initial hash, 
> right? So I can imagine a situation where a string must be interned at 
> runtime (constructed on-the-fly) and where you might see some runtime 
> performance issues for long strings vs. short strings.

It's hard to imagine a scenario where you're creating a string at 
runtime which is not at least O(n) on the size of the string you're 
creating. However, Lua's hash function only examines a maximum number 
of character (*not* the first k characters, but rather k characters 
spread through the string), so it is not dependent on the length of the 
string. Arguably, there are more collisions with long strings as a 
result of the partial hashing, but I haven't actually observed this in 
practice.